Women’s Issues in Transportation: Summary of the 4th International Conference, Volume 2: Technical Papers (2011)

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34 Postpartum Fatigue and Driving Relating experiences, Thoughts, and Opinions 12 Weeks After birth Kerrie Livingstone, Kerry Armstrong, Patricia Obst, and Simon Smith, Centre for Accident Research and Road Safety, Queensland, Australia Fatigue in the postnatal period is such a common expe- rience for most mothers that the term “postpartum fatigue” (PPF) has been coined to describe it. when new mothers experience extreme fatigue, it follows that their physical health, mental health, and social wellbeing are negatively affected. It is interesting to note that there is a distinct lack of empirical investigations focusing on the link between PPF and increased risk of injury, par- ticularly when the links between fatigue and increased risk of road crashes are well documented. The purpose of this investigation was to undertake pilot research to develop an understanding of the duration of PPF and the performance impairments experienced by new moth- ers when involved in safety-sensitive activities such as driving a motor vehicle. Semistructured interviews were undertaken with women (N = 24) living in Southeast Queensland, Australia, at 12 weeks afer they had given birth. Key themes were identified, with a particular emphasis on understanding the link between the partici- pants’ experience of PPF and the impact this had on their overall cognitive and physiological functioning as well as their experience of the driving task. Sleep–wake data were also collected, and the Karolinska Sleepiness Scale was used to evaluate the potential crash risk for this group of mothers. It is proposed that the findings of this investigation could be used to improve current knowl- edge among new mothers and practitioners regarding the mechanisms and consequences of fatigue and to inform interventions that lead to a decreased risk of injury asso- ciated with PPF. Sleep- and fatigue-related driving is well documented as being a significant contributory factor in fatal and serious injury crashes (1, 2). Fatigue and sleepi- ness are seen to be the largest identifiable and preventable causes of injury within the transport industry, surpassing the rate of drug- and alcohol-related incidents (1). Stud- ies suggest that 20% of all motorists on the road have fallen asleep at least once while driving (3). Factors that may contribute to driver sleepiness and crashes include sleep debt, shift work, prolonged work hours, time of day, time spent awake, time on task, type of road, risk- taking behavior, age, gender, sleep disorders, alcohol and other drugs, and monotonous road conditions (1, 4). Sleep, alertness, and performance are linked to the body’s 24-h biological clock (1). The effects of the fol- lowing conditions often result in sleepiness, tiredness, drowsiness, and fatigue: being awake when biologically programmed for sleep, restricted sleep over a period of time, and extended wakefulness (1, 5). Sleepiness can be defined as difficulty remaining awake even while carrying out activities and is related to circadian and homeostatic influences (6). Estimates of the proportion of crashes attributable to sleepiness vary considerably, with some research suggesting that sleepiness is a factor in 1% to 3% of crashes in the United States (4), whereas research in Australia estimates that sleepiness is a contributing factor in up to 33% of crashes (7). Research suggests that lack of sleep (e.g., 4.5 h compared with 7.5 h of sleep), can lead to significant impairment of driving performance (8), with individuals who obtained less than 6 h of sleep being twice as likely to be involved in a dangerous event while driving (9). Similarly, Connor et al. found a strong association

35POSTPARTUM FATIGUE AND DRIVING between levels of acute driver sleepiness and the risk of an injury crash (10). They found that participants who iden- tified any degree of sleepiness were 11 times more likely to be involved in an injury crash when compared with drivers in the most alert group. Fatigue is reported as the most common complaint of women following childbirth (11–16). To quantify the scale of the problem, the Australian Bureau of Sta- tistics recorded 280,000 mothers in 2007 who gave birth to 285,000 babies (17). This fatigue experienced by mothers is generally known as postpartum fatigue (PPF). Researchers have described it as the exhaustion and diminished ability to perform mental and physical activities that mothers experience in the postnatal period (15, 18–20). Although fatigue was originally intended as a formal expression of tiredness (21, 22), efforts have since been made to demarcate these terms along with the commonly used synonym “exhaustion” as separate but related concepts. Despite efforts to conceptually distin- guish fatigue from other labels that hold similar connota- tions, the terms “exhaustion” and “tiredness” frequently appear as descriptors of fatigue in the literature. Although it is important to make note of the language used in this area, it is not the intention of this paper to further the debate regarding the definitions of fatigue. women often believe that PPF is a temporary condi- tion that subsides as routine activities are reestablished (23). Research has shown, however, that PPF becomes progressively worse within the first 6 weeks after child- birth (12, 20, 24–26). These and similar findings have defined PPF as occurring in the first 3 months after child- birth (27), and it has been suggested that symptoms of fatigue may persist for as long as 18 months after child- birth for more than 50% of women (28). PPF is frequently portrayed in terms of physiological and psychological dimensions (15, 25). The physiologi- cal factors discussed can be classified as normal or path- ological in nature and include labor and delivery issues, anemia, and hemorrhaging (29). Mode of delivery is a commonly examined physiological factor in this area of research, with evidence suggesting that women who have caesarean sections as opposed to vaginal births experi- ence higher levels of PPF (30, 31). Anemia is defined as a reduction in the blood concentration of hemoglobin and is characterized in the postpartum period by a defi- ciency of iron in the blood (32). Anemia can be caused or made worse by blood loss (hemorrhaging) experienced during or after giving birth (33). Although some studies have found no evidence that iron deficiency anemia or postbirth hemorrhaging contribute to PPF in the first few months after delivery (34), anemia has been linked to women experiencing PPF 3 months after childbirth (35). Other physiological factors that are flagged in the litera- ture as potential contributors to PPF include postpartum infection, thyroid dysfunction, and pain (32, 36). within the psychological factors, depression is the predominant factor studied in PPF research. The rela- tionship between fatigue and depression in general has been a source of contention in scientific communities for decades and has spilled over into postpartum research. Postpartum depression (PPD) is considered a separate but related concept to PPF; however the degree of overlap and causal relationship between these conditions remains unclear. Past research has implicated PPF as both a cause and effect of PPD (37); yet there appears to be some con- sensus among researchers that PPF is one of a number of contributing factors to PPD (38, 39). Milligan et al. con- clude that PPF and PPD are distinct concepts that at times overlap in meaning and measurement (23, 27); however, they expanded on this assertion by revealing that women in the postpartum period only felt depressed when they experienced high levels of fatigue. This suggests that the relationship between these conditions may resemble more of a stage rather than a continuous model. Another area that has been explored is the impact of situational factors such as demographics, social support, and breastfeeding. Considerable work has been devoted to investigating these factors; however, the findings have not been consistent across any of the studies or variables studied. For example, research regarding maternal age has produced mixed results, with some studies reporting no relationship between age and PPF (34–36), whereas other research has found that more mature women reported lower levels of PPF (40). This conflicting result has also been reported for number of children. Gard- ner reported that mothers with two to three children reported higher levels of fatigue (40), whereas Larsen (41) and Hoffman (42) reported that mothers with one child recorded more fatigue responses than mothers who had three or more children. A key area of research relating to the contributing factors to PPF is the sleep loss that mothers experience as a result of recurrent infant night waking. Over the years, researchers have devoted much attention to inves- tigating fatigue by focusing on the harmful effects that sleep deprivation can have on cognitive performance and motor skills. For instance, Krueger reported a 25% to 40% drop in cognitive performance after one and two nights of total sleep deprivation, respectively (43). Other research has examined the effects of continuous sleep loss and found that performance on tasks requiring cognitive skills, vigilance, and psychomotor skills signifi- cantly deteriorated in stages over 36 to 42 h and then 66 to 72 h of sleep deprivation (44). In light of the studies highlighting the link between sleep loss and psychomotor performance, it is noteworthy that an extensive search of the literature found no studies specifically addressing PPF and crash risk. Researchers have attempted to quantify the harmful effects of fatigue by drawing comparisons between per-

36 wOMEN’S ISSUES IN TRANSPORTATION, VOLUME 2 formance impairments induced by total sleep depriva- tion and those induced by alcohol intoxication (45). For instance, Dawson and Reid conducted an experiment in which participants either remained awake for 28 contin- uous hours or consumed 10 to 15 g of alcohol at 30-min intervals until their mean blood alcohol concentration (BAC) reached 0.10% (46). In both conditions, cognitive psychomotor performance was measured by way of an unpredictable tracking task at 30-min intervals from the start of the session. The results indicated that after 17 h of sustained wakefulness, cognitive psychomotor perfor- mance had deteriorated to a level equivalent to a BAC of 0.05%. Further findings revealed that 24 h of sustained wakefulness resulted in performance decrements equiva- lent to a BAC of 0.10%. This research (46) and more recent work (47–49) concluded that moderate amounts of sleep deprivation can result in impairments to cogni- tive and motor skill performance that are equal to or greater than the legal BAC limit for driving. Fatigue researchers across other disciplines have shown that partial sleep deprivation, which results in cumulative sleep debt over time (50), can lead to fatigue and impaired performance under various types of condi- tions. For instance, in one study, sleep was limited to approximately 5 h per night for seven consecutive nights for 16 adults (51). Participants showed significant per- formance and mood deterioration over this period, with scores for fatigue, confusion, tension, mental exhaustion, and stress steadily increasing and vigilance performance scores steadily decreasing. The overall findings indicated that there was a cumulative effect on performance and mood. Similar research has shown that accumulative sleep debt can cause significant reductions in cognitive, vigilance, and memory tasks over shorter periods, as evi- denced when sleep time for participants was restricted to 4 h per night over 2 and 4 days (52, 53). The link between road crashes and sleepiness or fatigue, or both, is well established (2, 10). Research has also dem- onstrated that driving between 2 a.m. and 5 a.m. increases a driver’s risk of a crash by 5.6 times and that less than 5 h sleep during the past 24 h increases crash risk by a factor of 2.7 (10). Further, Åkerstedt et al. investigated whether retrospective sleep–wake data could predict actual road crashes (54). The predicted sleepiness values were trans- formed to a scale with nine steps analogous to the Karo- linska Sleepiness Scale (KSS), which were used in logistic regression analyses. Åkerstedt et al. found a highly signifi- cant odds ratio for each incremental step of sleepiness on the output sleepiness scale. These researchers place nor- mal alertness levels during the day between Levels 3 and 4 on the sleepiness scale, and from their data, it can be seen that a driver with a score of 6 is approximately five times more likely to be involved in an injury crash and that a driver with a sleepiness score of 9 is 24 times more likely to be involved in an injury crash. The current study investigates performance impairments in postpartum women when undertaking safety-sensitive activities and, particularly, what these decrements repre- sent in relation to the driving task. The obvious implica- tions for driving are that fatigue and sleepiness can lead to decreased attention, which in turn can lead to falling asleep while driving. Thus, the researchers felt it was important to include a separate measure of the participants’ level of sleepiness while driving. The KSS was chosen for two rea- sons: first, it has been demonstrated that falling asleep at the wheel in a driving simulator is always preceded by an increased KSS score (55), and second, previous research allows for the 9-point scale to be converted to an odds ratio of the associated crash risk, which allows inferences to be made regarding the crash risk of potential drivers. This research comprises an initial exploration of PPF, and it is not the intention of this paper to fully explore the wide variety of factors indicated in the literature. Rather, the research team focused on the duration of PPF and the mother’s individual experience of PPF. The literature on PPF highlights problems within the first 6 weeks of the postpartum period; the present research col- lected data at 6, 12, and 18 weeks to further explore the duration of PPF. The interviews conducted with partici- pants were done at week 12. The selection of this period was to determine whether PPF persisted past the initial 6 weeks; it was decided not to wait until 18 weeks after birth in case PPF had waned or disappeared entirely. Method Participants The participants were mothers who had just given birth to a baby and met the following criteria: had not given birth via caesarean section; had not ever been diagnosed with hypothyroidism; had not at any time in their life experi- enced a depressed mood or a loss of interest in pleasure that lasted for 2 weeks or more; and had not developed within the first 6 weeks iron deficiency anemia or any other postpartum infection or inflammation. Participants were recruited either through a Queensland University of Technology electronic noticeboard or via advertise- ments placed on various parenting websites. A total of 25 mothers were recruited; however, one withdrew from the study. Interviews were conducted with 24 participants whose ages ranged from 22 to 39 years, with a mean age of 30.25 years [standard deviation (SD) 5 4.86]. Materials The interviews were guided by a semistructured inter- view developed by the research team and designed to

37POSTPARTUM FATIGUE AND DRIVING explore the issues related to PPF. As there was no known previous research on PPF, the researchers were unable to draw on previous questionnaires. The KSS is a measure of instantaneous sleepiness and is measured on a 9-point Likert scale, as follows: 1 equals very alert, 3 equals alert, 4 to 6 equals neither alert nor sleepy, 7 equals sleepy, and 9 equals very sleepy. Partici- pants recorded their level of sleepiness for each driving episode at week 12 after birth for 7 days. Procedure Ethical clearance was granted from the University Human Research Ethics Committee. Participants were screened to ensure they met the inclusion criteria for the study. Both qualitative and quantitative data collection meth- ods were used. The data discussed in this paper came from a qualitative semistructured interview conducted at 12 weeks after birth. The purpose of the interview was to discuss the participant’s thoughts and experiences of sleepiness and fatigue since giving birth. The interview also asked participants to talk about the differences, if any, they saw between sleepiness and fatigue; the causes of fatigue; the impact that having a baby had on their daily routine; and strategies they might be using to cope better with sleepiness and fatigue. The interview did not explicitly ask participants about transport-related issues; however, these issues were highlighted in topics concern- ing how PPF had affected their daily life. All interviews were audio recorded. The quantitative method consisted of both a sleep– wake diary for participants to use in recording their sleep patterns and those of any children and a questionnaire that asked participants about themselves, their overall sleepiness and well-being, and any incidents. The sleep– wake diary and questionnaire were sent to the partici- pants and completed at 6, 12, and 18 weeks after birth; however, the diary and questionnaire data are not the focus of this paper and will be reported elsewhere. Par- ticipants were compensated with a $20.00 department store gift card for completing each of the four data col- lection points. Data Analysis The audiotape discussions were transcribed verbatim by the interviewer and were analyzed and coded using the- matic analysis. Concepts were identified as themes if they were expressed with frequency, extensiveness, or intensity (56). The first author, who conducted the semistructured interviews, also performed the analysis; however, she held frequent consultations with the other authors to improve the validity and reliability of the coding. The coauthors were particularly useful in identifying themes and inter- pretations that needed further clarification or explanation. The authors’combined efforts have resulted in a thorough and well-justified analysis that provides a comprehensive and accurate reflection of the data received. The KSS data were compiled from one question in the sleep–wake diary that related to the respondent’s level of sleepiness while driving at week 12 after birth. Results Qualitative Data The interviews conducted with participants ranged from 9 to 46 min (mean 5 22.35 min, SD 5 8.91 min). The interviewer noted that when answering the questions, some participants displayed disorganised thinking pat- terns, which was apparent in the indirect manner in which they answered the questions. A number of par- ticipants commented, “not sure if that answers your question.” To deal with the indirect nature of the data collection, the interviewer often interrupted the partici- pant and paraphrased the pertinent information relating to the question asked, with the intention of eliciting a yes or no response, and then moved on to ask the next question. The process of interviewing participants using a semistructured interview can often lead to tangential conversations. In the case of the mothers interviewed in this study, it is unclear whether the disorganised thinking patterns observed were connected with the experience of tiredness or fatigue in the postpartum period. It is pos- sible, given the range of interview times, that there may have been preexisting individual differences in the com- munication styles of the participants. The primary focus of this paper was centered on a thematic analysis of the performance impairment expe- rienced by postpartum women. It is not the intention of this paper to further the debate regarding either the academic or theoretical definitions or the mechanisms of fatigue. It is important, however, to contextualize participants’ comments by discussing the difficulty the mothers found in defining and differentiating tiredness, sleepiness, and fatigue, and the general impact of fatigue on this cohort. Fatigue Is More Than Sleepiness Many participants commented that while fatigue is linked with sleep, it is more than the feeling of sleepi- ness or tiredness alone. Participants reported that while a nap during the day alleviated their immediate feeling of sleepiness, it failed to lessen their overall feeling of fatigue. For example:

38 wOMEN’S ISSUES IN TRANSPORTATION, VOLUME 2 Lack of sleep is more mechanical, when the body just says ‘that’s it.’ Sleep could be likened to hunger or thirst, just a certain point where the body will just shut down. with fatigue, all sorts of an emo- tional spectrum of feelings . . . where the thought of having to get up to brush my teeth is agoniz- ing, overwhelming, all sorts of irrational emotions, no coping mechanisms, extreme irritability, over- whelmed a lot. (Participant 4) I find that if I have a day nap I feel okay for the afternoon; short-term solution really, but I still just feel exhausted—fixes the next 12 hours but not the whole situation. I wouldn’t feel so sleepy but I would still feel fatigued. (Participant 17) In terms of fatigue, I need something more than sleep; my body is wanting something deeper than sleep, a real sense of rest. (Participant 4) The theme of fatigue being something that can be fixed by sleep alone was echoed in the participants’ comments about the impact fatigue had on their daily routines. Sev- eral mothers expressed that they did not have a daily routine and it was difficult to know from one day to the next how much their day would vary. There was a real sense when speaking with these mothers that the fatigue was more than sleepiness and was the result of the level of tasks that needed to be completed in their day. For example, for many of the mothers, simple housework activities such as vacuuming the floor or planning and cooking an evening meal became complex and required more cognitive resources than they had at the time. Furthermore, this group of mothers expressed that the high level of unpredictability in the type of tasks and the length of time to complete a task was fatiguing. More- over, this was a particular issue for the mothers during the night, and the impact on “normal” sleep patterns appeared to have the most effect on the mothers’ levels of fatigue. For instance, the frequency of feedings varies based on the age of the baby, and many of the mothers in this study were subject to four-hour feedings. when the time the mother needs to feed the baby, settle the baby, and then get back to sleep herself is taken into account, in most cases there is not much time for quality sleep before the next round of night feedings is due to begin. It appears that the existence of this high level of unpre- dictability in the number and timing of tasks is in and of itself fatiguing for this group of mothers. For instance, one mother described it as “physically doing too much during the day, and mentally trying to concentrate on too many things” (Participant 23). It perhaps can be summed up as the cumulative effect of lifestyle changes, plus a lack of routine, plus a high level of unpredictabil- ity in tasks that equates to the feeling of fatigue. The content of this theme highlights that the mothers in this study see fatigue as something that is deeper than a physical need for sleep. The comments expressed draw attention to the impact fatigue has on every aspect of their daily life functioning and raises several concerns. Tasks that were once automatic and did not require large amounts of cognitive resources (e.g., preparing meals) have now become complex tasks. The major concern that this raises is how it affects the driving task, which for an experienced driver is largely an automatic process. Cognitive and Physiological Impact of Fatigue Another theme that emerged from the interviews was the cognitive and physiological impact of fatigue. Some of the following comments outline this group of mothers’ experience: It’s hard to predict until you are in it; it can be debilitating sometimes and have an effect on nor- mal mental functioning. (Participant 4) Fatigue is that point where you are so tired you don’t make sense when you talk to people or it’s difficult to have a conversation. (Participant 11) Realizing that I’m not functioning very well because of fatigue and lack of sleep. . . . There is a sense of getting worse and not coping—physical feelings like an endless hangover and a flu-like feel- ing. (Participant 4) It was really exhausting. I really couldn’t perform any task or anything. (Participant 3) It is emotionally and physically draining, but if I had more sleep I would be able to better cope with everything. (Participant 2) The biggest difference was the snappiness, the length of it. You know that you will have lack of sleep; there have been times that I have been so fatigued that I have felt faint. (Participant 17) These comments illustrate that for new mothers, there is an overwhelmingly negative effect from the cumulative impact of sleep deprivation and fatigue on their normal life functioning. It appears that fatigue is both the physi- ological and cognitive lack, whereas sleepiness is a tran- sient state. while the interviews raised the cognitive aspect of PPF, a notable subtheme that was repeated often across the interviews was the inability to concentrate

39POSTPARTUM FATIGUE AND DRIVING and the impact this had on the mothers’ life function- ing. It appears that new mothers have difficulty in con- centrating; one mother described it as the “fuzziness in your head” (Participant 2). Another mother described it as “Not having that mental sharpness . . . not think- ing ahead clearly, not being able to plan, being vague” (Participant 17). One mother also stated that “the level of confusion in the first 6 weeks is quite extreme. I can remember thinking ‘what am I supposed to be doing?’” (Participant 18). Another interesting state- ment combined aspects of concentration, memory, and cognition to highlight that these processes are closely intertwined and that when an individual experiences negative functioning in one area, it affects the overall system of cognition. This mother expressed it as fol- lows: “I have really noticed the effect on my mem- ory and cognition” (Participant 12). Another mother described it as the inability to “juggle as many tasks” (Participant 19). Several of the mothers also reported that they had problems in following a conversation when they were feeling fatigued, and if they were the speaker, that they would often forget what they were saying and be unable to complete their sentence. Further comments described their thinking as disorganized; for example, “don’t feel like thoughts are coherent” (Participant 17). In line with the previous discussion regarding the increased workload of mothers, one of the new mothers made this observa- tion: “You do become more forgetful, but not sure if it is because you have a newborn in the house and there are a million and one things to do or if I’m just more tired” (Participant 7). Regardless of how these mothers describe their expe- rience, it is apparent from the statements that the impact of fatigue on the study participants did have a consid- erable cognitive component that negatively influenced their life functioning. Furthermore, an alarming aspect of the statements made by this group of mothers sug- gested a decrease in their awareness of their environment and that instead of resting, they pushed on because tasks still needed to be done and the baby still had needs to be met. For example, one mother said, “If you are tired during the daytime, and something needs to be done, you don’t sit down and have a rest, you continue to do it in the haze” (Participant 16). Some mothers talked about how their lack of con- centration translated to the driving environment; for example, “I guess when you are out and about driving . . . you almost feel like you are on autopilot” (Par- ticipant 18). This participant went on to comment that she had experienced this just recently, in an instance where she had no recollection of the journey home. She said, “I was driving home and luckily all the lights were green, because all of a sudden I thought ‘how did I get here?’ So I had just cruised along all the way home and all the lights had been green and I just followed the traf- fic and I drove” (Participant 18). Impact of Fatigue on the Driving Task The statements in the previous section relating to the driving task highlight that driving requires a high level of attentional resources that for many new mothers is lacking. It appears that because of both the cognitive and physical impact of fatigue, driving becomes an auto- matic process, which often means they have no recall of their interaction within the road environment. One of the most disturbing findings from these interviews came from one participant who made statements that suggested a disconnection between mind and body. Her comments intimate that regardless of their intention to drive in a safe manner, new mothers may be unable to control the actions of their body. Following are some statements illustrating these sentiments: Inability to control what the body is doing; for instance, when driving the other day I thought I was braking when I was accelerating. (Participant 4) Mentally it didn’t matter how much I so passion- ately told myself to focus. I could not control my eyes. They were wandering everywhere, my heart was pounding, and while I was really focused I just couldn’t control it. I think it had to do with lack of sleep. I was alert, mentally saying to myself “stay awake,” but I really couldn’t, it was really out of my control. (Participant 4) At other times, the participants commented that their level of confusion and decision-making ability made the driving environment an extremely complex task. For example, one mother stated: It is the confusion that comes with it, and I can remember driving around a car park and it was almost empty and still not being able to choose which park I wanted—do I want to be close to the shops, which exit do I want to be closer to, do I want to be under the shade or out of the shade, do I want to drive in or reverse out? (Participant 18) In addition to this general feeling of not being able to concentrate, this group of mothers talked about how driv- ing had been different since giving birth and that it was harder to cope with everyday occurrences such as having children in the car or listening to the radio. For example: The driving has been different. I am more tired . . . and I have children talking in the background so it

40 wOMEN’S ISSUES IN TRANSPORTATION, VOLUME 2 really knocks my concentration. I wish I could have a glass screen up so I couldn’t hear them. Having added noise and stresses makes it hard. (Participant 16) I find that I have to turn off the radio when driving. I can’t concentrate. (Participant 15) An unexpected but noteworthy finding was that this group of mothers appeared to be self-regulating their driving exposure without being aware that doing so was a protective driving behavior. The behaviors described include choosing to drive less, avoiding the driving task when tired, and choosing to walk or catch public trans- port. For example, one mother stated “. . . before the baby was born I would do things like drop off videos or pop down to the shops to buy bread or milk. I really don’t do that now” (Participant 9). An interesting theme that came out of the interviews was that if they had more knowledge about the level of fatigue and tiredness they would experience after giv- ing birth, many mothers would have done more plan- ning and preparation prior to the arrival of their baby to reduce their need to leave the house. For example, “If I had of thought more about it, I would have had lots of things sorted like meals, breastfeeding bras and tops, because I didn’t want to drive” (Participant 4). Further, many of the mothers also planned when their driving tasks occurred. Following is a statement that illustrates this finding: I was careful with long drives and generally did them early in the day. I would have a lot of strat- egies. I would pick the time of day—not after lunch—have food to eat in the car. I would also want another adult in the car who was going to be awake. . . . I would choose better times and days to take a long journey. (Participant 13) The final theme that emerged from the interviews con- cerned the influence that the study exerted on this group of mothers’ awareness of the safety aspect involved in driving. For example: when I started the week 6 data collection, it made me more alert while driving. (Participant 22) Doing the study has made me realize how little sleep I am actually getting, and it makes me think about the safety and driving on the road. (Partici- pant 17) The diary and questionnaire made me realize and think about how many mothers are on the road— you know, school pick-up time, that is a bad time of the afternoon for mothers and kids to be sleepy and fatigued. It is also really congested around schools. (Participant 4) Quantitative Data The KSS data were compiled for all participants and comprised the number of times they had driven within a 7-day recording period, the duration of their driving time, and, finally, the associated KSS score for each driv- ing episode. There were two participants who did not record any driving episodes at week 12 after birth. On average, participants (n 5 22) drove 8.35 times (SD 5 4.35) for approximately 40 min (SD 5 16.38; range, 18 to 96 min). There were a total of 192 driving episodes across all participants; of these, 35 driving episodes (18.2%) occurred with a KSS rating of 6, 21 driving episodes (10.9%) occurred with a rating of 7; five driv- ing episodes (2.6%) occurred with a rating of 8; and one driving episode occurred with a rating of 9 (0.5%). Overall, 32% of the driving episodes were rated by par- ticipants as occurring at a KSS score of 6 or above. discussion of Results This research explored the performance impairments experienced among a cohort of postpartum women when undertaking safety-sensitive activities, particularly driving a motor vehicle. The interviews highlighted that within this group of participants, PPF persists longer than the initial 6 weeks after giving birth. The thematic analysis showed that the fatigue the participants experienced was more than sleepiness and tiredness and could be characterized as being deeper than a physical need for sleep. Furthermore, the impact that fatigue had on their everyday life function- ing was dramatic, manifesting itself as difficulties in their cognitive processing and physiological performance. The mothers interviewed noted that they were often unable to concentrate, which affected their ability to plan and orga- nize simple tasks such as preparing the family meal. The particularly concerning aspect of this group of mothers’ experience of PPF related to the impact it had on their driving. The statements made by participants sug- gested that their concentration levels had dropped to such a degree that they could not recall their interaction within the driving environment. It also appeared that they experi- enced a level of confusion that affected their decision mak- ing and ability to deal with additional stimuli while driving, such as the radio or children talking in the background. Perhaps the most disturbing comment related to the driving task came from one participant who experienced a discon- nection between mind and body, an “inability to control what the body is doing.” This participant said, “I thought I was braking when I was accelerating.”

41POSTPARTUM FATIGUE AND DRIVING Research conducted by Krueger suggests that an indi- vidual’s cognitive performance drops by up to 40% after one or two nights of total sleep deprivation (43). Other research that reports that continuous sleep loss signifi- cantly affects tasks requiring vigilance and psychomotor skills (44) has serious implications for mothers suffering from interrupted sleep patterns. Statements implying that the mothers in this study continue to do safety-sensitive tasks, such as driving, when they are sleep deprived means that there is a cohort of drivers on the road who lack the necessary cognitive and attentional resources required for the task to be carried out in an optimal manner. The sleep–wake predictor scores recorded for the par- ticipants in this study while driving found that 32% of the driving episodes undertaken occurred at a KSS score of 6 or above. Åkerstedt et al. deemed that a KSS score of 3 was equivalent to normal daytime alertness and an odds ratio for an injury crash marginally above zero (54). That is, an individual with a KSS sleepiness score of 6 is five times more likely to be involved in an injury crash; an individual with a KSS score of 7 is eight times more likely; one with a KSS score of 8 is 15 times more likely; and one with a KSS score of 9 is 25 times more likely to be involved in an injury crash (54). within this sample, there were 62 driv- ing episodes where the odds of being involved in an injury crash were between five and 25 times more likely than if the individual had recorded a sleepiness score of 1 to 5. The KSS results found in this cohort of postpartum mothers provide an opportunity to estimate the scale of the crash risk associated with PPF in the Australian popula- tion. In 2007, 280,000 women gave birth. Assuming that approximately 80% of these women hold a valid driver’s licence, and given the average of eight driving episodes per week carried out by the current cohort of mothers, there are potentially 1.8 million driving episodes per week performed by postpartum mothers. In this study, 32% of the driving episodes were undertaken with the associated risk of an injury crash being between five and 25 times more likely. Therefore, it could be proposed that there are potentially 575,000 driving episodes per week performed by postpartum mothers in Australia that may be between five and 25 times more likely to involve an injury crash. Researchers in the area acknowledge that fatigue affects attention and vigilance and is associated with difficulty in maintaining “skilled performance” on tasks such as driv- ing (57). It has also been suggested that fatigue is a major contributor to driver error and that activities such as driv- ing require sustained performance over time and involve greater cognitive effort than physical effort (58, 59). Activ- ities requiring complex cognitive processes include sus- tained vigilance, selective attention, and complex decision making (58, 59). Thus, the research suggests that fatigue and sleepiness contribute to deterioration in performance (58). Therefore, it is apparent that new mothers represent an “at risk” group who are worthy of further research to develop interventions specifically aimed at addressing their concerns and needs. Together, the qualitative and quantita- tive data for week 12 suggest that fatigue leads to decreased attention and concentration, which in turn lead to errors while driving and substantially increase new mothers’ chances of being involved in an injury crash. It should be noted that some of the participants in this study self-regulated their driving exposure by avoiding driv- ing entirely, using alternative modes of transport, or choos- ing the best times to drive (e.g., time of day or type of road). This demonstrates that some of the mothers in this study were aware that their ability to drive safely was impaired at certain points in time. while this self-regulation was not mentioned by all of the participants, it is possible that they all may have self-regulated their driving exposure. what is interesting is that none of the participants identified it as a protective driving behavior or strategy. Therefore, it would be useful to develop an intervention aimed at increasing new mothers’ awareness of how debilitating PPF really is and their accuracy in determining their level of PPF. The intervention would need to focus heavily on a variety of factors, including the following: • The vast difference between fatigue and sleepiness; • The physical and cognitive limitations of fatigue (e.g., practical examples of the relationship between physical and cognitive symptoms and the driving task); • Strategies to assist mothers in coping with both the physical and cognitive limitations of PPF and to help them decrease their risk of injury on the road (e.g., alter- native modes of transportation or driving at times when they are more alert); and, • Ways of informing new mothers that these symp- toms extend well past the initial 6-week period that exists in the published literature. while the findings of this research are important, it should be acknowledged that the data collected did not take into consideration a variety of sociodemographic factors that were discussed in the literature. These fac- tors all appear to be important influences on a mother’s experience of PPF; however, because of the preliminary nature of the study, it was outside the scope of resources to include all of these variables. It is recommended that further research address these factors. Finally, the data collected from the participants represent a limited sam- ple of their driving and was not exhaustive of the driving task outside of the 7-day recording period at week 12. AcknowledgMent The authors thank the Centre for Accident Research and Road Safety, Queensland, Australia, for funding this research.

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