At the beginning of the testing stage and early issue of the vaccine (in the UK, at least) there was official reticence about offering it to pregnant women or women who were trying to conceive, stemming from not having pregnant women in the original test groups (to avoid any potential risk). So the advice that pregnant/trying to conceive/breastfeeding women could safely take the vaccine was delayed.
I think that delay caused some hesitancy (and refusal) which continues to exist despite the later clarifications and well-publicised results confirmations.
