What's safe (and what isn't) when you're having sex during pregnancy. Sex positions to try: "Anything goes during the first trimester," Dr. Streicher says. poll of pregnant women revealed that back-door sex was suddenly very enticing, tread. Have Hot Pregnancy Sex: The Best Positions for Every Trimester. These will feel comfortable —and freaking amazing. In general, you should avoid positions that have you on your back late in the second trimester and during the third. Also Since it has you on your back, it's best kept to the first trimester. However, the truth is that sex during pregnancy is safe and harmless, though there are exceptions. But if you are healthy and do not suffer from any complications of It is best to abstain from sex during the first trimester of your pregnancy. Spooning: This is often termed as lazy sex position and requires.