In the second trimester (weeks 14 to 28), baby goes through major development, forming more detail and getting all of those brand new body parts into working order. The organs further develop and start functioning, getting ready for life in the outside world. Baby also grows eyebrows, eyelashes and fingernails (aww!), and his or her wrinkly skin becomes covered with fine hair (called lanugo) and a waxy protective coating (called vernix). In the second trimester, you'll have the option of finding out baby's gender, as the genitals develop and can be viewed during an ultrasound (usually at your 20 week appointment). You'll start to feel baby too, as the little acrobat starts flipping and kicking around. In addition, by the end of the second trimester, baby will be able to swallow, hear, pee and suck his or her thumb.
Expert: American College of Obstetrics and Gynecologists. Your Pregnancy and Birth. 4th ed. Washington, DC: ACOG; 2005.