39 weeks of pregnancy is about 9 months. More specifically, it is the fourth week of the ninth month, which means the baby is full-term and could be born at any time.
At this stage, the baby usually measures around 20.5 inches (52 cm) and weighs about 7.9 pounds (3.6 kg). All organs are fully formed, but the brain and lungs are still maturing, and the immune system continues to strengthen with antibodies passed from the mother.
The pregnant person may feel more tired, notice more vaginal discharge, have Braxton Hicks ("practice") contractions, or lose the mucus plug, which is a jelly-like substance that may mean labor is getting close. The baby is usually head-down, putting pressure on the cervix as the body prepares for birth.
It is important to continue regular prenatal checkups and let your OB-GYN or midwife know if you notice signs such as strong, frequent contractions, vaginal bleeding, leaking of fluid, or any other signs of labor.