Timing Intercourse After LH Surge Does Not Influence Baby's Sex
No, timing intercourse 24-48 hours after peak LH cannot influence whether you conceive a boy or girl. The evidence consistently shows that sex selection through timing of intercourse relative to ovulation is not clinically reliable or effective.
The Evidence Against Sex Selection by Timing
The research on this topic is clear but often misunderstood:
Older theories have been refuted: A prospective study specifically examining the relationship between coitus timing and offspring sex found that intercourse close to ovulation does NOT favor male conceptions, contrary to popular belief 1. In fact, this study showed the opposite trend—male conceptions were associated with longer intervals (>2 days) between intercourse and fertilization 1.
The effect is too subtle to be practical: Even when statistical associations have been found, the clinical relevance assessment concluded that "the influence of coital timing on the sex ratio is overall quite subtle and is not a practical method to alter the sex ratio for individual couples" 2.
Conflicting and unreliable data: One small study from Nigeria claimed 94.9% success with timing methods 3, but this has not been replicated in rigorous research settings and contradicts the broader body of evidence showing no clinically meaningful effect 2, 1.
What Actually Matters for Conception Success
Instead of focusing on sex selection, the timing that matters is for achieving pregnancy itself:
Optimal fertility window: Intercourse should occur 1-2 days before ovulation for the highest pregnancy rates, as sperm can survive 3-5 days in fertile cervical mucus 4.
After LH surge: If using LH testing, intercourse or insemination should occur within 24-30 hours after LH surge detection for optimal pregnancy rates 4, 5.
The egg's viability: The egg remains viable for only 12-24 hours after release, making pre-ovulation intercourse more effective than post-ovulation 4.
Common Pitfalls to Avoid
Don't rely on timing for sex selection: The 24-48 hour window after LH surge you mentioned is optimal for conception, but has no reliable influence on the baby's sex 2, 1.
Avoid excessive stress from timing: Timed intercourse can create significant stress for couples, and there's evidence this stress may even hinder normal reproductive functioning 6.
Regular intercourse is better: Available data suggest that a coital frequency of at least a couple of times per week would help reduce stress while ensuring intercourse during the fertile window 6.