Preventing Low Birthweight Summary (1985) / Chapter Skim
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Causes of Low Birthweight
Causes of Low Birthweight
Pages 4-14
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From page 4... ...
Certain clinical conditions, discussed in the following section on risk factors, appear to cause changes in the hormonal environment and metabolic state of the uterus and cervix. These changes probably result from complex interactions involving progesterone, estrogen, oxytocin, and other hormones; prostaglandins; calcium ions; adrenergic agents and receptors; catecholamines; and uteroplacental blood flow.
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From page 5... ...
Risk Factors In the absence of adequate information about the basic causes of low birthweight, a large body of information has cleveloped about "risk factors," or factors whose presence in an individual woman indicates an increased chance of bearing a low birthweight infant. These factors, which will be outlined further in the following pages, are listed in Table I
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From page 6... ...
The committee's analysis of national and statewide trends in the whiteblack differential in low birthweight indicates that the gap is not closing. For the United States as a whole, the relative decline in white Tow birthweight rates between 1971 and 1981 exceeded the corresponding relative decline in black low birthweight rates.
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From page 7... ...
Nonimmune status for selected infections such as rubella F Poor obstetric history including previous low birthweight infant, multiple spontaneous abortions G
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From page 8... ...
, some types of genitourinary tract infections, and limited access to high-quality prenatal care. The effect of socioeconomic status probably represents the sum of many factors, each of which may increase the risk of poor pregnancy outcomes.
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From page 9... ...
Obstetric History The history of a woman previous pregnancies is of prime importance in the prediction of a subsequent Tow birthweight infant. A detailed study of the weights and gestational ages of all births in Norway from 1967 through 1973 showed that a premature first birth is the best predictor of a premature second birth and that growth r~t~r~l~tinn in ~ [irct .
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From page 10... ...
However, short interpregnancy interval is not associated with an increased risk of Tow birthweight if the previous pregnancy ended in a fetal death. Previous Induced Abortion Because about 1,500,000 legal induced abortions occur annually in the United States, the committee believed it was important to assess the impact of such procedures on the incidence of {UGR and preterm delivery in subsequent pregnancies.
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From page 11... ...
women of lower socioeconomic status. A further analysis of numerous risk factors among white mothers only indicated that, except for period of gestation, weight gain has the strongest impact on birthweight.6 Behavioral and Environmental Risks Smoking Smoking is one of the most important and preventable cleterminants of low birthweight in the United States.
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From page 12... ...
Evolving Concepts of Risk A desire to improve the health care professional's ability to identify pregnant women at risk of a low-weight birth has lect researchers to study a variety of other possible risk factors. Those described in the full report include stress, uterine irritability anct the notion of "triggering factors," certain cervical changes cletected before labor begins, inadequate plasma volume expansion, and progesterone deficiency.
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From page 13... ...
There is no conclusive evi- o dence, however, that maternal em- ~ ployment per se increases the risk of ° Tow birthweight. ,: Numerous reports suggest a link between stress and conditions that ~increase the risk of JUGR and pre- x term labor, such as preecIampsia, but ~ relatively little ciata exist to support a O strong, direct relationship between maternal psychological stress and low birthweight.
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From page 14... ...
The not infrequent occurrence of Tow birthweight deliveries in Tow-risk women suggests that additional research is needed to improve the predictive capability of these systems. It also indicates that clinicians must be alert to the possibility of Tow birthweight even in pregnant women judged to be at low risk of such an outcome.
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