October 6, 2022 – Pamela Jock She always had regular periods, even when she was 50 and knew menopause was on the horizon. But shortly after receiving the second of two COVID-19 vaccine series in June 2020, her cycle began to change. At 52, he may already be in perimenopause, but Jock had to wonder if the vaccine might have played a role. It turns out that the answer to her speculation is “maybe.”
A new study was recently published in BMJ, He took a deep dive into the possible link between the COVID vaccine and menstrual irregularities. The investigation, led by Alison Edelman, professor of obstetrics and gynecology at Oregon Health & Science University, was prompted by more than 30,000 reports of cycle changes at the UK’s Medicines and Healthcare products Regulatory Agency (MHRA).
Using data from a menstrual tracking app called Natural Cycles, the study collected numbers from more than 20,000 women from around the world. The researchers considered the three menstrual cycles before vaccination, and at least one cycle after. They compared this to four menstrual cycles in a group that did not receive the vaccine.
The results showed that, on average, the vaccinated women delayed their periods 0.71 days after the first shot. Those who received two vaccines during one cycle experienced an increase in cycle length to 4 days, on average. This tracks Jock’s experience. “My cycle stretched to 30 days, as opposed to the usual 26,” she says. “Then I had a gap between cycles for a few months.”
This is where the link to the vaccine cycle gets more murky. Given Jock’s age, the biggest gap between cycles may be in perimenopause, especially since the study only examined women between the ages of 18 and 45, who already had regular cycles. But Jock still wonders. “After I had my first booster shot in the fall of 2021, my period was back to normal, appearing every 26 days,” she says. “But it was too heavy and I was tired and exhausted.”
Follow-up revealed anemia as a result. When I asked about the link to the irregular vaccination cycle, Jock says, “The doctor didn’t think there was a connection, and that it was probably perimenopause.”
What’s going on
Whether it’s in the age group of people in the study or beyond, like Jock, the relationship between the COVID vaccine and menstrual cycle changes can stem from several things, he says. Esther Goldsmith, Exercise Physiologist with Orreco Bioanalytics.
“This may be affected by the time in your cycle you get the vaccination,” she says. We know that changes in estrogen and progesterone in the menstrual cycle can affect the immune system and our immune responses. That’s why I think it’s really interesting that the study shows that those who took two doses in the same cycle were the most affected.”
The Orreco dataset — which often focuses on female athletes — showed that the vaccine could have other effects, too, that may play a role.
“We’ve also seen that the vaccine can affect oxidative stress and inflammation, which are things we measure through point-of-care blood analysis,” Goldsmith says. “Inflammation can affect symptoms, so using heuristics, the vaccine may also cause an illegitimate change in PMS symptoms.”
Shaggig DeNoble, MD, Master’s Degree in Gynecology and Laparoscopy in North Jerseysays she hears from many patients that their periods came later than expected, and/or that they were having periods that were heavier than usual after the vaccine — as well as after contracting a COVID infection.
“I remind them that many things can change our cycles, including travel, changing seasons, and stress,” she says. This happens all the time, and there are no long-term effects. I assure them that their cycles will return to normal.”
The research found that in most cases, normalization occurred within one or two cycles after the vaccine, which is consistent with what DiNobel patients also reported.
Putting minds at ease
While research may have established a possible link between the vaccine and abnormal menstrual cycles, Goldsmith and DeNoble both maintain that the injection does not affect fertility.
“I get a lot of phone calls from women who worry that their fertility may also be at risk due to menopause,” says DeNoble. “But fertility is not diminished by the vaccine.”
Jock says she is thankful that fertility is not something she cares about anymore. “I’d probably be worried if that was the case,” she admits.
Such concerns are unwarranted, Goldsmith says, and she wants women to set aside any concerns. “An abnormal period is a very normal response to something physiological that is a major event for your body to deal with,” she says. “Menstrual cycles can be incredibly sensitive to change of all kinds, whether it’s nutrition, lifestyle, stress or the immune system. So we shouldn’t be surprised that they will respond to things like vaccines. This is probably not a new phenomenon, but it probably hasn’t been.” documented in the past.
Now armed with the results of the research, DeNoble says it will be easier to educate patients about what to expect with reinforcers.
“It’s very important for us to be able to warn patients about potential side effects, and it’s also important to put their minds at ease,” she says.
Goldsmith recommends that women keep track of their cycles and document any changes – vaccination or not.
“We should all pay attention to our cycles and make sure we are taking care of ourselves in these times in order to reduce the stress to which the body is exposed,” she says.
While Jock won’t know for sure if her irregular cycles are caused by the vaccine or perimenopause, she is keeping an eye on what happens when she soon receives the bivalent COVID vaccine. “I’m curious to see if this leads me down the same path,” she says.
Regardless of the inconvenience caused by an abnormal cycle, Jock doesn’t regret receiving the vaccine, she says, “I’d rather stay healthy and avoid COVID.”