Unless your doctor tells you otherwise, it is perfectly safe for you to have sex throughout your pregnancy. However, towards the expected birth date, your size may make many positions uncomfortable for you. Penetration may be easiest if you lie on your side and your partner enters from behind. Oral sex and mutual masturbation should cause no problems. Some women fear that sexual activity or orgasm may trigger off labor but sex cannot induce labor unless the baby is due anyway, when the prostaglandin present in the man's semen may cause it to start.
The sex drive of some women decreases during the first trimester of pregnancy. This may be due to tiredness and nausea, or to a hidden belief that it is 'not right' for a mother to enjoy sex. The problem will usually disappear of its own accord. In some women, the sex drive actually increases during the middle three months (the second trimester) of pregnancy, and some claim that their lovemaking is more satisfying than ever before. This may be because the high level of circulating hormones means that a woman can be stimulated more easily and reach a pitch of sexual excitement more quickly than when not pregnant. A pregnant woman's sexual organs breasts, nipples and genitals - are especially highly developed, which probably increases sexual awareness. Finally, there is of course complete freedom from the worry of getting pregnant, which allows a deeper level of 'letting go'.
Some women and their partners worry that sex may harm the unborn child, but such fears are groundless. The fetus is protected from infection by the plug of mucus at the neck of the womb. In rare cases, infection can occur, but this is usually due to lack of normal hygiene precautions or having sex with several different partners. The baby is also protected against being squashed by the amniotic fluid in which it floats in the womb. Avoid over-athletic sex because it will be uncomfortable for you, but don't worry about hurting the baby. Sex should not cause a miscarriage in a normal, healthy pregnancy.
You can resume sex after childbirth as soon as it is comfortable to do so. Women who have had an episiotomy (in which the perineurn is cut to facilitate birth), will probably feel sore for at least three weeks. When you feel confident that your wound has healed, begin to re-establish your sex life, taking it slowly and gently and using a lubricating jelly if necessary to prevent scar tissue causing discomfort or pain. It is important to establish sexual contact with your partner as soon as you can, as you will both need to get close again. If you still feel sore, remember there are other ways of giving and receiving affection. Don't let your partner feel that you are lavishing all your care and attention on your baby and excluding him from your love.