07/07/2021
More than a year has passed since Covid-19 infection rates first hit
peak levels but only now, in the knowledge that receptors for SARS-CoV-2 are
present in the ovary, are we able to assess the effect of the virus on
reproductive function. A new study has shown that the ovarian reserve of women
previously infected with the virus was not adversely affected, and that their
chance of success from fertility treatment remained as it was before infection.*
The study,
which monitored hormone levels in women having IVF at the IVI Clinic in Madrid between
May and June 2020, was described by Dr Maria Cruz Palomino at the online annual
meeting of ESHRE.
All the
women in the study had baseline hormone measurements before starting treatment,
which included measurements of anti-Mullerian hormone (AMH, as 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 – although its reliability as a marker of general female
fertility is more disputed.
The study
included 46 patients having IVF whose baseline measurements of AMH 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 Palomino. However, the results
did show a slight decline in AMH measurements in those predicted to be normal
responders, which Dr 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”.
Several
studies reported so far have been reassuring about the effect of Covid-19
infection on female fertility, and this provides further reassurance for those
planning fertility treatment with IVF. Experts have 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.
This, as Dr
Palomino explains, was a small study and not robust enough for emphatic public
health conclusions, but it does join others in suggesting that ovarian
function, as reflected in AMH measurements, is not affected by 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, uterus,
vagina and placenta. The SARS-CoV-2 virus has been said to interrupt female
fertility through regulating ACE2. This has caused some anxiety for women
contemplating fertility treatment, and this latest 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
previous infection. “Nevertheless,” said Dr Palomino, “we could assume that the
chances of success of fertility treatment remain intact.” The results reflect
those of a recent study from Wuhan, China, which similarly found that average
sex hormone and AMH concentrations of women of child-bearing age with COVID-19
were not different from those of age-matched controls (1).
* Ovarian reserve
Ovarian
reserve describes the ability of the ovary to produce eggs for fertilisation
(natural and medical) and pregnancy. Because of the ovary’s fixed store of eggs
which depletes over time, ovarian reserve is known to decline, beginning at
around the age of 35 and continuing to the menopause, when reproductive
function stops. Diminished ovarian reserve and decline in egg quality are known
to explain the decline in fertility with age.
Tests of
ovarian reserve, such as AMH and counting small early follicles in the ovary
(by ultrasound), will thus give an indication of how many egg follicles remain
in the ovary, but will not provide an accurate prediction of fertility. Some
women will get pregnant with low markers of ovarian reserve, while others with
high measurements will not. However, AMH test results have been found to
correlate closely with how women respond to ovarian stimulation for IVF,
thereby predicted as normal, low (few eggs produced) or high responders (many
eggs produced and with them a risk of ovarian hyperstimulation syndrome).
1. See Li
K, Chen G, Hou H, et al. Analysis of sex hormones and menstruation in COVID-19
women of child-bearing age. Reprod Biomed Online 2021; 42: 260-267.
Autor: