in the male sterilization procedure called vasectomy. Also called ductus deferens.


A surgical procedure in which segments of the vas deferens are removed and the ends tied to prevent passage of sperm. Vasectomy should be regarded as permanent, although reversal is possible in some cases.


Withdrawal (coitus interruptus)

Removing the penis from the vagina just prior to ejaculation.

Women in fertile age (WIF)

Females of childbearing age, typically defined as between ages 15 and 44 or between ages 15 and 49.



The fertilized egg before it starts to divide.

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