The ovarian reserve of women previously infected with SARS-CoV-2, the virus causing COVID-19, is not adversely affected, and their chance of success from fertility treatment remains as it was before the infection, finds a study.

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Ovarian reserve describes the ability of the ovary to produce eggs for fertilisation (natural and medical) and pregnancy. The study, led by researchers at IVI Madrid, a fertility clinic in Spain, provides further reassurance for those planning fertility treatment with IVF. The findings were presented at ESHRE's 37th annual meeting taking place online from 26 June to July 1. The study described intrauterine infection via placental or congenital routes as unlikely and reported that perinatal infection found at and after delivery was a more likely explanation for any neonatal infection.

The team monitored hormone levels, in all 46 women having IVF in Spain between May and June 2020, which included measurements of anti-Mullerian hormone (AMH) -- a marker of ovarian reserve. AMH has become a widely used measurement in fertility clinics in recent years, able to predict how patients might respond to ovarian stimulation in IVF. It suggested they would be normal or low responders to ovarian stimulation when treatment began. "Generally, the data showed no variation in AMH levels before and after SARS-CoV-2 infection, and we could assume that the chances of success in their fertility treatment remained intact," said Dr Maria Cruz Palomino from IVI Madrid.

However, the results did show a slight decline in AMH measurements in those predicted to be normal responders, which Palomino said was not a "radical decrease" and unlikely to compromise ovarian reserve -- nor, she added, "can we attribute this variation to SARS-Cov-2 infection". There have been concerns because the virus invades its target cells by binding to the ACE2 receptor, which is widely expressed in the ovaries (as well as the uterus, vagina and placenta). This has caused some anxiety for women contemplating fertility treatment.

But the study suggests that, while there was a variation in levels of AMH as a marker of ovarian reserve, this variation appeared dependent on patient response to ovarian stimulation, not on the previous infection. "Nevertheless, we could assume that the chances of success of fertility treatment remain intact", said Palomino.