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Article
June 30, 1956

FACTORS AFFECTING NORMAL EXPECTANCY OF CONCEPTION

JAMA. 1956;161(9):855-860. doi:10.1001/jama.1956.02970090081016
Abstract

• The most probable number of liveborn children to be expected by a woman who marries at age 17 and who makes no attempt to thwart her normal fecundity is calculated from the data of three different ethnic groups as about 13. Periods of gestation are normally separated by mean periods of about 15 months of involuntary sterility. These probably embrace some six months of postpartum lactation amenorrhea, perhaps three months of anovulatory cycles after resumption of the menses, and about six months required for conception after ovulation is reestablished.

The length of time for a first conception to occur is calculated from data from six geographical areas; the median lies between two and three months. The previous use of contraceptives does not lengthen the time required for conception in women achieving pregnancy. The optimum coital frequency for conception is found to be four times or more weekly. The decline of coital frequency with age is but one factor in the strong antifertile influence of length of marriage.

Promptness of conception after abandonment of contraception was determined in 58 newly delivered or pregnant women who had been delivered of the pregnancy previous to the current one by cesarean section. The median conception time for this group was the same as for 935 multiparous patients vaginally delivered, 2.0 as compared with 2.1 months. Race, social background, parity exclusive of age, and intellectual level when dissociated from contraceptive practices were not found to have any effect on fertility.

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