At 25 weeks, a pregnancy is 6.25 months along. According to WebMD, in the 25th week of pregnancy, a baby is in its 23th week of development and measures 8.8 inches from the top of its head to its bottom. The average weight of a fetus during the 25th week of pregnancy is 1.5 pounds.
According to the University of California San Francisco's Benioff Children's Hospital, the 25th week of pregnancy occurs in the second trimester, which lasts from the week 14 to week 26. According to What To Expect, during the 25th week of pregnancy, the fetus begins to grow capillaries under the skin, changing it from translucent to a more opaque coloring. Also at this time, the fetus begins to develop blood vessels in its lungs and the nostrils begin to open.
Although not yet able to breathe, the fetus can use its nostrils to inhale and exhale amniotic fluid. According to both WebMD and What To Expect, a woman in her 25th week of pregnancy may experience painful hemorrhoids, along with constipation, heartburn and indigestion. During this point in the pregnancy, WebMD explains that the fetus may begin to open its eyelids, and the heartbeat may be audible without the use of a stethoscope.