Husband doesn’t want me to tell my sister if we get pregnancy until 2nd trimester.

Hi all, wanted to get your onion on the situation and how to mediate. We are going through IVF and just had a transfer done. If we end up pregnant I want to tell my sister I’m pregnant since she knows we’ve been trying for a really long time. Recently we’ve had a couple arguments that have affected the way my husband feels towards her, he’s just being protective of me. But that doesn’t change the fact that we’ve always told each other everything. He’s super intent on not telling anyone until the 2nd trimester and I want to be able to tell my family right away. If anything bad were to happen I’d want them to know anyway as a support system. But he doesn’t want anyone to know. I’m just not sure how to go about it cause I want to respect his wishes but I also feel like mine should be heard to.