Widespread rumors that mRNA vaccines negatively impact fertility are unfounded, according to new research from the department of obstetrics and gynecology at Israel’s Sheba Medical Center.

The team studied 36 couples undergoing a second round of vitro fertilization (IVF) treatments. All had received both doses of the Pfizer Covid-19 vaccine between the two rounds.

None of the couples showed any differences in parameters such as sperm quality, semen volume, ovarian stimulation or proportion of high-quality embryos compared to their IVF cycles prior to vaccination.

In fact, one-third of the couples conceived in the post-vaccination IVF round whereas the usual success rate is about one quarter.

The observational study, published in Reproductive Biology and Endocrinology, concluded that the “mRNA SARS-CoV-2 vaccine did not affect patients’ performance or ovarian reserve in their immediate subsequent IVF cycle.”

Lead author Dr. Raoul Orvieto, director of Sheba’s IVF Fertility Clinic, said they decided to do the study because many people fear the possible effects of the vaccines on fertility.

He noted that this is the first study to demonstrate and publish that the vaccine has no effect on male or female fertility, but that larger studies with longer follow-up will be needed to validate his team’s observations.

Orvieto also pointed out that some preliminary studies indicate Covid-19 illness may lead to decreased ovarian function or semen quality. His group in a previous study “could not demonstrate any effect of COVID-19 infection on the ovarian stimulation characteristics and embryological variables of patients’ IVF treatments, except for a reduced proportion of top-quality embryos.”

Which means being vaccinated against Covid-19 seems to be a safer bet for couples trying to conceive.