Why is it that men, especially, are afraid to have sex with their pregnant partners? Why is it that doctors are famous for writing prescriptions for sex as the due date approaches? Why is it that during that second trimester women are more amorous than their partners? Why don't people have more sex when they are pregnant?
It is perfectly safe to have sex as much as you like. If the pregnancy has no complications, that is. In the first trimester, you may not like even the thought of sex and that's to be expected. With the symptoms ( nausea, vomiting, low back pain and intermittent cramps, constipation and fatigue ), it's understandable; rest up for the second trimester. Women are willing and able and there is no need to hesitate. Maybe it is hormones, maybe it's the increased blood supply to sexually stimulated organs. Who cares? By the third trimester, you are back to "not interested" for obvious reasons.
Sex will NOT cause a miscarriage. It doesn't hurt the developing fetus and they have no clue what you are doing down there. The growing uterus and its contents are well insulated by the mucous plug and the amniotic fluid surrounding your baby.
Positions my need to be repositioned and any position that is comfortable is just fine. Time to experiment. Oral sex is okay but blowing air into the vagina is never okay anyway.
The contraction-like orgasms that we experience during sex aren't labor contractions and do not become labor contractions and as long as the doctor hasn't cautioned against sex for medical reasons, you are good to go. If your cervix is "ripe' and you are ready to go into labor, some people advocate it, although there is no good reason to know if that is what really starts the process. Don't have sex if you are at risk for preterm labor, have bleeding, if you are leaking water from your vagina, if you have cervical incompetence or any placental placement that indicates a previa.
After the baby is delivered, you may have sex after six weeks. That last check-up will insure that you are completely healed and back in working order. Do not be alarmed if you aren't in the mood. If you are breast-feeding, the estrogen depletion will deplete the sexual drive. So will sleep deprivation and the general fatigue that follows childbirth, sometimes for months.
There are many ways to say I love you. Doesn't necessarily mean intercourse, especially when you don't want to. Intimacy is about communication and appreciation. I always say a home-baked cake ( either party ) goes a long, long way.