What is the Shettles method?
The Shettles method is a theory from the 1960s that timing sex relative to ovulation can influence a baby's sex: sex close to ovulation for a boy, and 2 to 3 days before for a girl. It is based on a belief that male-producing sperm are faster but shorter-lived. Good-quality studies have not found that timing changes the odds.
What the method says
| Hoping for | Shettles suggests |
|---|---|
| A boy | Sex on the day of ovulation or just after, deep penetration, alkaline conditions |
| A girl | Sex 2 to 4 days before ovulation, then stop, shallow penetration, acidic conditions |
What the evidence shows
A landmark study of couples trying to conceive, published in the New England Journal of Medicine in 1995, tracked the timing of sex against ovulation and found no link between timing and the baby's sex. Later research hasn't found reliable differences in speed or survival between X- and Y-bearing sperm either. The odds stay close to 50:50 whatever the timing.
Timing does matter for getting pregnant at all: sex in the 2 to 3 days before ovulation gives the best chance. Following Shettles' "girl" timing can actually make conception less likely, because it avoids the most fertile days of the fertile window.
Using our calculator
Our boy or girl ovulation calculator shows Shettles-style timing for curiosity, alongside your real fertile days. Think of it as fun, not a method. Medical sex selection is only possible with IVF and genetic testing, which is restricted in many countries. Learn more about ovulation predictor kits and the LH surge.
Trying for a particular sex can add pressure to an already emotional time. It's okay to enjoy the theory lightly and let go of the result.
Frequently asked questions
What is the success rate of the Shettles method?
Shettles claimed 75 to 90%, but controlled studies found no effect beyond the natural roughly 50:50 chance.
Does diet change a baby's sex?
There's no reliable evidence that diet, douching or positions change the sex of a baby.
Sources
- Wilcox AJ et al. Timing of sexual intercourse in relation to ovulation. NEJM (1995)
- ACOG: Fertility Awareness-Based Methods of Family Planning
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
Ovulation calculator boy or girl: what timing can (and can't) doOvulation calculator boy or girl: see the Shettles timing dates for your cycle, and what the research says about choosing your baby's sex. Kind and honest.
Ovulation: definition and meaningOvulation is when an ovary releases an egg, usually 12 to 14 days before your next period. Signs, timing, the fertile window, and how it affects mood.
Fertile window: definition and meaningThe fertile window is the six days each cycle when sex can lead to pregnancy. How it's worked out, when it falls, and why it isn't a contraceptive tool.Fertile window calculator: when am I most fertile?Free fertile window calculator: see the days each cycle when pregnancy is most likely, for your next 4 cycles. Private, estimates only, not contraception.
Conception calculator: when did I conceive?Conception calculator: enter your due date to find your likely conception date (due date minus 266 days) and the window of days the sex could have happened.