Ovulation triggers in anovulatory women undergoing ovulation induction

Use of medicines to help release eggs in women with infertility being treated with medicines to increase the growth of eggs

Korula George1, Mohan S Kamath2, Raju Nair3, Prathap Tharyan4 

Bangalore Baptist Hospital, Reproductive Medicine Unit, Bangalore, Karnataka State, India 
Christian Medical College and Hospital, Reproductive Medicine Unit, Vellore, Tamil Nadu, India 
Matha Assisted Reproductive Centre(m.arc), Reproductive Medicine Unit, Kottayam, kerala, India 
Christian Medical College, South Asian Cochrane Network & Centre, Prof. BV Moses Centre for Evidence-Informed Health Care and Health Policy, Vellore, Tamil Nadu, India 

Ovulation triggers in anovulatory women undergoing ovulation induction. Cochrane Database of Systematic Reviews 2014, Issue 1. Art. No.: CD006900.

To read the full review please follow this link: DOI: 10.1002/14651858.CD006900.pub3.

Review question

In women being treated with medicines to help eggs to grow (called ovulation induction), Cochrane authors wished to know whether adding medicines (called ovulation triggers) that help to release the egg (ovulation) would lead to more women having babies without causing harm compared with not giving them ovulation triggers. We found two randomised studies.


Medicines that are given orally (e.g. clomiphene citrate) or by injection (e.g. gonadotrophins) are used to help eggs to grow in women who are unable to have children because they are not able to produce eggs (anovulation). In these women, instead of waiting for the eggs to be released spontaneously, additional medicines (called ovulation triggers) are often used (e.g. human chorionic gonadotrophin (hCG)) to help release the eggs. They are thought to improve the chances of ovulation occurring. They also help to control when ovulation occurs. This helps in timing more accurately when sexual intercourse should take place, so that the woman's chances of becoming pregnant are better. These ovulation triggers are given when the sac in which the egg is developing (follicle) is thought to be fully developed, based on ultrasound scans. However, this method is not always accurate and may lead to the ovulation trigger being given before the egg has matured. If eggs that are not fully developed are released, the chances of a successful pregnancy could be reduced. Couples are expected to have sex 36 hours after the ovulation trigger is given, and the need to stick to this timing may increase psychological stress for the couple. Ovulation triggers also add to the cost of treatment and occasionally may cause serious adverse events.

Study characteristics

The two studies included in this review randomly assigned 305 women being treated with clomiphene citrate to help eggs to develop to additionally receive a medicine (urinary hCG) to trigger their release or to receive no additional treatment. We found no trials comparing other ovulation triggers given with other medicines used for ovulation induction. The evidence is current to November 2013.

Key results

Giving women on clomiphene citrate additional urinary hCG may not increase their chances of delivering live babies, ovulating or becoming pregnant. Multiple pregnancies, miscarriages and preterm deliveries were not more common with or without an ovulation trigger. No serious adverse events were reported in either study.

Quality of the evidence

We cannot be certain whether ovulation triggers are better or worse than no ovulation triggers in women undergoing ovulation induction because not enough women were included in the two trials for definite results to be obtained. Larger trials in women undergoing ovulation induction that compare different ovulation triggers versus no additional treatment are needed.