It's not safe/it will hurt the baby. One of the most commonly voiced questions is whether sex—that is, sexual intercourse/penetration—will be harmful to the pregnancy or baby. Most of the time, this is completely untrue. Unless your doctor or midwife specifically advises against having intercourse (typically for a history of miscarriage or preterm labor), sex is safe and should be enjoyed as desired. Baby is well protected by not only the bag of water and membranes, but a closed cervix, which is typically in a higher than normal position during most of pregnancy. Light bleeding or spotting can be very common after sex during pregnancy and should not be cause for concern. As always, when in doubt, ask your care provider.
I won't be interested. It can be true that sexual desire can plummet during pregnancy. It also can be true that your sex drive can go into overdrive during pregnancy! There's no way of knowing which camp you will fall into until you're there. And while you may be disinterested in sex during early pregnancy due to fatigue and nausea, your libido could return to normal after the first trimester. Go easy on yourself, be honest with your partner, seek support from others and know that however you're feeling about sex during pregnancy is likely normal.
It will hurt. In general, sex during pregnancy shouldn't hurt. That said, sex during pregnancy can feel different, and whether or not you enjoy the way it feels (emotionally and physically) is an individual response. If you do experience pain with sexual acts or positions that you normally enjoy, get creative and experiment with other positions or techniques. Sexual intimacy comes in many forms! If pain becomes a recurring or major issue, contact your doctor or midwife to help you find out why. There could be an underlying medical cause.
I won't be attractive to my partner. Pregnancy is a time of immense physical change in a relatively short time frame. It's understandable to feel concerned about body image during pregnancy, especially in a particularly exposed setting like the bedroom. The reality is that most people truly enjoy and take delight in the beauty of a changing body that is growing a child. Even so, it's important to talk about your concerns and come up with ways to make each other feel more comfortable. If sexual intimacy (or lack thereof) becomes a major issue for both of you, consider seeking counseling or therapy to address your concerns.