Avoid hairstyles that pull on your hair, such as ponytails, weaves, and tight braids.
Avoid overly hot hair dryers and/or styling implements (including irons and hot rollers). Riccardo Maggiore, renowned celebrity hairstylist and the owner of the Riccardo Maggiore Salon in Manhattan, recommends, "If possible, you should let your hair air dry instead of blow drying it."
Avoid daily shampoos since these remove your hair's natural oils and may aggravate the dryness. Most stylists claim that two or three weekly shampoos are sufficient to remove excess build-up of dirt and particles. Use shampoos and conditioners that contain biotin and silica (both help strengthen hair).
Be gentle when handling wet hair, as it's more liable to tear, break, or become even more brittle. Wide-toothed combs and brushes with smooth tips may be gentler on your scalp, as will conditioner that helps untangle without pulling.
Finally, before you haul those shears out of your closet and decide to tackle your locks in desperation, try for a new style. Avoid going too short as this sometimes means more, rather than less, maintenance (and remember, time will become a scarce commodity once you give birth).
If you're concerned about weight gain, longer hair may help camouflage any excessive weight around your facial features, softening your looks; and layering may help give your hair a fuller look.
A professional stylist can help you find a look that will help you feel your best as you enter one of the most wondrous stages in a woman's life: motherhood.