Babies start moving just after 6 weeks in the womb, with their first moves being simple head or body bends you can spot on an ultrasound! By 7-8 weeks, they begin doing spontaneous startles that often trigger smooth, flowing movements called general movements. As they grow, babies also begin showing isolated arm and leg motions, and even tiny twitches during sleep, which may help their brains learn how the body works. These early moves are like baby "practice sessions," helping them explore their bodies and build a map of their little world before they’re even born!

A baby’s tongue starts forming as early as 4 to 5 weeks into pregnancy, and by week 8, the first tiny taste buds begin to appear. Many more buds develop between weeks 11 and 13, but they don’t start sending taste signals to the brain until weeks 14 to 15, when nerve connections begin to form. By about 30 weeks, most of those taste buds and their nerve pathways are fully working, letting babies taste flavors from their mom’s diet as they pass into the amniotic fluid. So yes, babies really do get their first flavor experience before they’re even born!

Between weeks 3 and 8 of embryonic development, a process called organogenesis takes place, during which the three germ layers, ectoderm, mesoderm, and endoderm, begin forming all of the major organ systems. By the end of week 8, important systems such as the heart, lungs, digestive tract, brain, liver, and pancreas have started to develop and are in position to continue growing and maturing. Starting in week 9, the fetal period begins, shifting the focus to the growth, development, and proper functioning of these organs and body systems.

A small-scale study that observed five sets of twins in the womb found that social interaction between them begins as early as the 14th week of pregnancy. The researchers noted a steady increase in these interactions, and by week 18, the twins were reaching out to each other more frequently than to themselves or the uterine wall.