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Every pregnant woman’s sex life is different, but often, levels of desire follow the course a roller coaster as much as the pregnancy itself does.

During the first trimester, physical and hormonal changes may deter you from getting busy, while increased vaginal lubrication and blood flow to the pelvis in the second trimester usually boosts the libido. Yet in the third trimester, the body tends to go into nesting phase, often reducing sex drive. In fact, 92 percent of pregnant women had problems with arousal, orgasm and satisfaction after 36 weeks of pregnancy, an April 2017 study in the Alexandria Journal of Medicine found.

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Regardless of the course you and your partner take, here’s what to know before jumping into the sack with a baby on board.

1. Don’t: Have sex if you have a high-risk pregnancy.
A number of conditions may make sex inadvisable for you during pregnancy, Dr. Hilda Hutcherson, a professor of obstetrics and gynecology at Columbia University Medical Center in New York City, told Fox News. Those conditions include a placenta previa, a shortened cervix or a cervical cerclage (stitch) for an incompetent cervix, and preeclampsia.

2. Do: Make sex a priority if you can have it.
Thanks to the hormone oxytocin, which is released during orgasm, sex can reduce stress and anxiety.

Sex can also help you strengthen the bonds with your partner before your baby is born, as studies show that the years after the birth of a baby are not only stressful, but they can cause your sex life to decline.

If you and your partner are up for it, having sex can help you stay connected, strengthen your relationship, and help you ease into your new life after your baby is born, Dr. Erica Marchand, a licensed psychologist in Los Angeles who specializes in sexual and relationship issues, told Fox News.

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3. Do: Try different positions.
In the first trimester when your belly is still small, any sex position will do. After about 16 weeks as your uterus gets bigger, however, missionary position or any position where you’re lying flat on your back isn’t a good idea.

“It can compress the big blood vessel behind the uterus called the inferior vena cava and restrict blood flow return to the heart and women will feel a little lightheaded or like their blood pressure is going down,” Dr. Alyssa Dweck, a board-certified OB/GYN in Mt. Kisco, New York, and author of “The Complete A to Z for Your V,” told Fox News.

Instead, try positions that take all pressure off the uterus: on top, side by side or from behind.

4. Do: Choose the right lube.
Thanks to pregnancy hormones, you’ll notice an increase in vaginal discharge, also known as leucorrhea, which can make the need for a sexual lubricant unnecessary.

If you do use a lube, however, stick with a water-based type and avoid petroleum-based lubrications, mineral oil or cooking oils, which can cause a change in the pH of the vagina or small nicks that promote infection, Dweck said.

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5. Do: Try other forms of intimacy.
If you can’t have sex or aren't feeling up for it, find other ways to keep the intimacy going strong in your relationship, like by kissing, cuddling, having oral sex, and engaging in mutual masturbation.

If you have oral sex, your partner should never blow air into your vagina because, although rare, it could cause a venous air embolism (VAE), a blocked blood vessel, which can be life-threatening for you and your baby, Dweck said.

6. Don’t: Have sex after your water breaks.
Of course, you should never have sex after your water breaks because of the risk for infection.

"Sex won’t start your labor if you’re full term or past your due date, but the prostaglandins in semen may help to ripen the cervix and orgasm can cause uterine contractions. So if you’re in the mood, there’s no reason not to do it.

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7. Do: Talk about it.
Just as your desire for sex can change throughout your pregnancy, your partner’s can as well. In fact, men’s testosterone levels can decline as pregnancy progresses, a December 2014 study in the American Journal of Human Biology found.

Pregnancy and the birth of a baby can change your sexual relationship, but if you keep the lines of communication open and work together, your sex life can be even better than it was before.