No, not at all worrying really. It’s fairly typical of vaccine trials (I’m a infectious disease researcher). The trials have only been ongoing since June. Women in the trials would have been asked not to get pregnant (and probably had to be on birth control to participate, which is normal in all pharma trials). There hasn’t been long enough for community use to see if there are any impacts on fertility and that isn’t something pharma trials can test due to ethics rules. It’s no more worrying than how any other vaccine or medicine is developed before it gets to market, except that in normal trials some people do get pregnant (against advice), so they kinda find out that info through the back door. We do know that COVID has some impact on pregnancy outcomes in certain populations, so you have to make an educated decision if you prefer a known risk or a as yet unknown one.