Timed intercourse: does it actually work?

If you’re trying for a baby, when is the best time to have sex? Many couples find it difficult and turn to purchasing “hormone monitoring kits” to help. But what is the evidence that these work? We asked experienced gynaecologist and fertility consultant Mr Parijat Bhattacharjee to review the studies so far and assess their conclusions:

Human beings have always wondered about when and sometimes ‘how’ to have sex to have a successful outcome, i.e. able to conceive.

Hippocrates (460-375 BC) mentions that a woman who is experienced in matters of childbirth will take note of when the sperm is retained and the precise day when she can conceive.

In the ancient Indian medical text, ‘Sushruta Samhita’ (600 BC-200 CE), the first 12 nights after stoppage of menstrual flow was considered ideal for conceiving a child.

10-15% of couples trying to conceive may have difficulty in conceiving. One of the reasons may be inappropriate timing of intercourse. To conceive one has to have intercourse about 5 days before to a few hours after ovulation (release of egg). ‘Timed intercourse’ is trying to predict (or identify) this ‘fertile period’ and increase the chances of spontaneous conception.

How do you work out when to have intercourse?

Predicting when you will ovulate is more difficult than many people think. A study from Australia suggests that although 68% of women believed they can accurately predict their ‘fertile period’ or ovulation, only 13% correctly did so.

Because of the difficulty involved, many couples use various ‘kits’ available to predict ovulation. These work on assessing urinary hormones (LH, oestrogen), basal body temperature, cervical mucus, calendar method and some even use ultrasound scans.

The evidence so far

Out of five studies, four suggested that there may be a slight increase in pregnancy rate with timed intercourse. They suggested that without timed intercourse the chance of conception is 13% and with timed intercourse it is between 14-23%.

Some couples may be worried about feeling stress and pressure from the use of hormonal kits. However, out of five studies, only one reported stress as an adverse event with timed intercourse.

Unfortunately, even though these were randomised control trials (supposedly best form of research), the quality of the trials was very poor, so the evidence is inadequate to suggest routine use of these kits at present.

Digital monitors

An observational study (lower quality evidence) in 2018 suggests hormonal digital monitors may offer better prediction of fertile period and ‘focussed intercourse’ over 24 menstrual cycles and may have a beneficial effect in achieving pregnancy.

An RCT (better quality study) in 2019 suggests there is no increased stress in using digital ovulation tests in helping time intercourse. From this point of view, a digital monitor may be better.

Conclusion: are they worth the cost?

Hormone kits are recommended if:

• you find it difficult to have intercourse every 2-3 days
• you are using artificial insemination to get pregnant, in which case a hormonal ovulation detection kit should be used to time intercourse on the day of the surge (LH).

Otherwise, there is insufficient evidence that hormone monitoring kits are effective and therefore they may not be worth the cost and potential stress.

NICE (National Institute of Clinical Excellence) suggests regular unprotected intercourse i.e. upto 2-3 times a week for 1 year in women less than 40 years of age gives a 80% chance of conception. Sperms survive inside the female reproductive tract for upto a week. Having intercourse 8 times a week does not affect sperm numbers though motility is optimum if intercourse happens every 3-4 days. The highest chances may be with intercourse within 2 days before ovulation (including the day of ovulation).