Title: Timing of sexual intercourse in relation to ovulation: effects on the probability of conception, survival of the pregnancy, and sex of the baby.

POPLINE Document Number: 110265

Author(s):

Wilcox AJ
Weinberg CR
Baird DD

Source citation:

NEW ENGLAND JOURNAL OF MEDICINE, 1995 Dec 7;333(23):1517-21.

Abstract:

A prospective study of 221 healthy women planning to become pregnant examined the timing of sexual intercourse in relation to ovulation to determine whether time factors influence the probability of conception, the pregnancy outcome, or the sex of the baby. Using urine analysis, the dates of ovulation were determined in 625 cycles. 192 pregnancies were indicated by increased levels of human chorionic gonadotropin, and 129 ended in live births. In every cycle in which pregnancy occurred, intercourse occurred at least once during the six consecutive days that ended with the day of ovulation. None of the 31 cycles in which no intercourse took place during this time span resulted in conception. The proportion of pregnancies ranged from 0.08 with intercourse on the first of these six days to 0.36 with intercourse on the day of ovulation. The probability of a live birth for any given cycle is 0.25 with daily intercourse, 0.22 with intercourse every other day, and 0.10 with weekly intercourse. No lower fertility (due to depletion of the number of quality of sperm) was found with higher frequency intercourse. Analysis of age of sperm versus survival of the pregnancy revealed that only 6% of the conceptions could be firmly attributed to sperm which was three or more days old, but a similar pattern was found in relation to intercourse/ovulation timing in pregnancies which ended in fetal loss or live births. Timing of intercourse in relations to ovulation had no influence on the sex of the baby. These findings suggest that the fertile period lasts about six days and ends upon ovulation and that sperm retain their fertilization ability in the female reproductive tract for about five days.

Keywords:

Research Report
Prospective Studies
Sexual Intercourse
Ovulation
Time Factors
Pregnancy Rate
Pregnancy, Planned
Pregnancy Outcomes
Sex Ratio
Studies
Research Methodology
Reproduction
Population Dynamics
Demographic Factors
Population
Fertility Measurements
Fertility
Reproductive Behavior
Pregnancy
Sex Distribution
Sex Factors
Population Characteristics