Nearly 4,000 women have suffered period problems shortly after getting their Covid jab, Britain's vaccines watchdog has confirmed.
The issues, normally involving 'heavier than usual' bleeding or a delayed period, have primarily affected women aged between 30 and 49.
The Medicines and Healthcare products Regulatory Agency (MHRA) said it had received 2,734 reports linked to the AstraZeneca jab up to May 17.
Another 1,158 reported menstrual changes after receiving Pfizer's and a further 66 were linked to the recently deployed Moderna jab.
Experts said the number of women suffering from period problems will 'definitely' be higher because many don't take the time to report it through official channels.
The figures, obtained by the Sunday Times, have raised questions about why menstrual changes are not included on the MHRA's list of Covid jab side effects.
But the regulator said a review into the issue concluded that the symptoms were not happening more frequently in newly vaccinated women than the general population. It said it would continue to 'closely monitor' the situation.
Nearly 4,000 women have suffered period problems after getting their Covid jab, according to Britain's vaccines watchdog
On its website, the MHRA said the number of reports was 'low in relation to both the number of females who have received Covid vaccines to date and how common menstrual disorders are generally'.
'The current evidence does not suggest an increased risk of either menstrual disorders or unexpected vaginal bleeding following the vaccines,' it adds.
'The MHRA will continue to closely monitor reports of menstrual disorders and vaginal bleeding with COVID-19 vaccines.'
