Sex in first few weeks ok?

Loryn • Mommy to b/g twins born june 20th, 2016 at 31 weeks. Now pregnant with #3! Due Spring 2019!
Hey all! I'm currently around 3-4 weeks pregnant and I'm curious if it's safe to have sex or not. I want to wait til we go to the Dr in a week or two but I feel bad for my husband, but I just want to be safe....anyone know the answer?