Your Baby at 17 Weeks

A Closer Look at Week 17

Week 17 brings a major structural milestone: your baby's skeleton is transitioning from soft, rubbery cartilage into hardened bone through a process called ossification. This transformation begins in the long bones of the arms and legs and will continue throughout fetal development and even into childhood. Calcium is a critical ingredient in this process, so ensuring adequate calcium intake through dairy products, fortified plant milks, leafy greens, or supplements is especially important right now.

The umbilical cord is also maturing this week, growing stronger and thicker to support the increasing demands of a larger, more active baby. The cord now contains one large vein (carrying oxygen and nutrient-rich blood to the baby) and two arteries (carrying waste products back to the placenta for disposal). It is coated in a thick, slippery substance called Wharton's Jelly that protects it from kinking and compression.

Round ligament pain is a very common symptom at this stage of pregnancy. The round ligaments are fibrous cords that run from the front of the uterus down into the groin, and as the uterus expands, these ligaments stretch and can cause sharp, sudden pains in the lower abdomen. The pain is most often triggered by sudden movements — standing up quickly, coughing, sneezing, or rolling over in bed.

While round ligament pain is harmless, it can be alarming if you don't know what it is. Moving slowly when changing position, supporting your belly with a hand when you cough or sneeze, and applying a warm compress to the painful area can all help. If the pain is persistent, severe, or accompanied by fever or bleeding, contact your healthcare provider to rule out other causes.