Review question

We reviewed the evidence on the effect of timed intercourse (using ovulation prediction) versus intercourse without ovulation prediction in couples trying to conceive.

Background

Many couples find it difficult to achieve a pregnancy and have concerns about their fertility. In each cycle, a woman is fertile from approximately five days before ovulation (egg release) until several hours after ovulation due to the limited survival times of the sperm and egg. Identifying this fertile period of a woman's menstrual cycle to guide the timing of intercourse may therefore improve conception (pregnancy) rates. This may reduce unnecessary medical treatment and costs of advanced infertility treatment, but it may also cause adverse events such as stress. The fertile period can be identified using different methods, including urine ovulation tests (dipstick devices that can detect changes in hormones released into the urine, signifying when ovulation will occur), fertility awareness-based methods (FABM) (including calendar tracking, monitoring changes in cervix fluid and body temperature), or identifying when the egg is released on ultrasound. This review aimed to assess the benefits and risks of timed intercourse on pregnancy, live birth, negative effects, and quality of life in couples trying to conceive.

Study characteristics

We found seven randomised controlled trials (a type of study where participants are randomly assigned to one of two or more treatment groups) comparing timed intercourse versus intercourse without ovulation prediction in 2464 women or couples trying to conceive. The evidence is current to January 2023.

Key results

We added three new studies at this update. The newly included studies strengthened our confidence in the effect of ovulation tests on couples trying to conceive.

We concluded that timing intercourse around the fertile period identified using a urine ovulation test probably increased the chances of pregnancy and live birth in women under 40 trying to conceive for under 12 months compared to intercourse without ovulation prediction. The results suggest that if the chance of pregnancy following intercourse without using urine ovulation tests is 18%, the chance following timed intercourse with urinary ovulation detection would be 20% to 28%. Moreover, if the chance of a live birth without urine ovulation prediction is 16%, the chance of a live birth with urine ovulation prediction is 16% to 28%. However, as many of the studies were funded by the manufacturers of the urine ovulation test, the results should be interpreted with caution. There is insufficient evidence to conclude the effect of timed intercourse on clinical pregnancy (ultrasound-confirmed pregnancy), adverse events such as stress, and quality of life. Due to limited data, we are uncertain of the effect of FABM in timed intercourse on pregnancy outcomes, adverse effects, and quality of life compared to intercourse without ovulation prediction.

Quality of the evidence

The overall quality of the evidence ranged from moderate to very low. Additional studies in this field are needed. The main limitations of the evidence were the small number of included studies, small study sizes, and potential for bias, given that many of the studies were funded by the manufacturer of the ovulation prediction device. As a result, the findings should be interpreted cautiously, and future studies may modify our conclusions.