Although 96% of the 10,064 vaccinated women in the study-- participants--received their first shot during their second or third trimester, the timing of the vaccination had no impact on the pregnancy, the study suggests.

In addition, as , the rate of preterm births--under 37 weeks of gestation--were marginally lower (4.9%) than the rate for unvaccinated women (7.0%). Considering the difference in the sample groups--roughly 36,000 were not vaccinated at the time of the birth--and the small difference, the discrepancy was considered statistically insignificant.

Although some women have reported heavier or more painful periods following the vaccine--an inflammatory or stress-induced response of the body, said Luxembourg  gynaecologist Marc Pfeiffer --the impact on fertility and the unborn child’s health has so far not been proven.

Instead, as the CDC and the Higher Council for Infectious Diseases point out, unvaccinated women, though not more likely to be infected, have higher risks of developing symptoms and landing in intensive care. This could lead to increased risks for the child and mother, says the CDC.