Does having sex later in a woman's ovulation cycle affect the sex of the baby, particularly for a woman with a history of traumatic pregnancy?

Does Timing of Intercourse During Ovulation Affect Baby's Sex?

No, the timing of sexual intercourse in relation to ovulation does not influence the sex of the baby. 1

Evidence on Sex Selection and Intercourse Timing

The highest quality prospective study directly addressing this question found no relationship between intercourse timing and offspring sex:

• In a rigorous prospective study of 221 women tracking 625 menstrual cycles with urinary hormone measurements to precisely determine ovulation, cycles producing male and female babies had similar patterns of intercourse in relation to ovulation 1
• For practical purposes, the timing of sexual intercourse in relation to ovulation has no influence on the sex of the baby 1

Contradictory Historical Theory

One older prospective study from 1984 suggested the opposite finding, but this has not been replicated:

• A small study (n=33 pregnancies) found a possible association between male conception and longer intervals (>2 days) between coitus and fertilization, though the authors themselves noted this "clearly refutes the theory that intercourse close to ovulation favors male conceptions" 2
• This finding was based on limited data and has been contradicted by larger, more rigorous research 1

The Fertile Window (Relevant Context)

While timing doesn't affect sex, understanding the fertile window is important for conception:

• Conception occurs only during a six-day period ending on the estimated day of ovulation 1
• The probability of conception ranges from 0.10 when intercourse occurs five days before ovulation to 0.33 on the day of ovulation itself 1
• The American Society for Reproductive Medicine recommends intercourse 1-2 days before ovulation for optimal conception chances 3

Special Considerations for Your Situation

Regarding the history of traumatic pregnancy mentioned in your context:

• The sex of the baby is determined at conception by which sperm (X or Y chromosome) fertilizes the egg, and this is a random biological process unaffected by intercourse timing 1
• No evidence suggests that timing intercourse differently would reduce risks associated with a previous traumatic pregnancy
• Any pregnancy planning after traumatic pregnancy should focus on appropriate prenatal care and risk assessment rather than attempting sex selection through timing