Remember, this pregnancy is a major event in your partner's life, too. Odds are, their seeming lack of interest has nothing to do with how they feel about you. Fear and anxiety about starting a family and being a parent (gulp!) may be causing your partner to take a step back. And, what with your swinging moods (don’t deny it!) and shifting hormones, they may be nervous about how you'll react (physically and emotionally) to sex.
Another possibility is your partner's tentative towards intercourse due to fear of hurting the baby. If this is the case, remind them that baby won't feel a thing, and if they don't believe you, drag them to your next OB visit and let the doctor do the talking. It also might be that your partner is uncomfortable having sex “in front” of your child. Sounds crazy, perhaps...but who says this is a rational time?
Whatever the case, open lines of communication are essential. Being honest about your own needs and fears will encourage your partner to do the same. If the truth is hard to hear—even the most loving, devoted partners can find intimacy tough during pregnancy—remember that this is a strange journey for both of you. Just like you, they're doing their best. And don't forget about other ways to stay connected. Back massages, foot rubs, holding hands, and kissing and cuddling can be just as romantic as anything else.