Stamp Collecting: Scientific evidence indicates that many fetuses enjoy the hobby of stamp collecting. One has to pass the time somehow and what better way than delving into the fascinating world of postage? Philately, with its multitude of colorful stamps, is ideal but often leads to premature childbirth due primarily to the intense excitement such a hobby generates. It has the added benefit of being educational and explains why so many fetuses leave the womb with an impressive knowledge of geography.
Gourmet Cooking: Fetuses have an amazingly well-developed sense of taste by the second trimester and many of them just love to throw together exotic dishes, all of which taste a little like placenta, not to be confused with polenta which is unavailable in most in-womb grocery stores including Costco. There is nothing like a good, hearty womb-cooked meal!
Gardening: Many fetuses take advantage of the warm, moist climate inside the womb to grow and nurture greenhouse plants. This is a fascinating hobby for these tiny developing creatures, particularly since they're already quite familiar with fertilization.
Charades: Twins (and their mothers) get a real kick out of charades according to most OBGYNs, although the required pantomime works better with twins and quadruplets (triplets confuse team formation.) Many fetuses simply cannot resist the amusement of a parlor game in the dark, dank confines of the womb. Hilarity abounds, although fetus laughter usually causes flatulence in the mother.
Golf: Since most fetuses already know what a woody feels like, they are natural golfers and many participate in the sport. Golf carts are rarely available, but the distances are short. If you're alone in there, you might be limited to the driving range but multiples make it far more exciting and competitive (although child therapists say it can lead to sibling rivalry.) Needless to say, the womb is also the perfect place for handball and squash due to the confines of the walls.
Carpentry and Interior Design: Hell, since you're stuck in there for nine long months you at least have to have some decent bookshelves and a coffee table. Many people are not aware of this, but wombs usually come unfurnished. Some fetuses have a real knack for making their environment both comfortable and classy and there's nothing like a womb with a view. Minimalist style is best due to space limitations so there's not much room for artwork, elaborate stereo systems or drapes. Some fetuses are better than others when choosing fabric.