Physical changes

Weight is gained during pregnancy due to increased appetite, fat deposition, and growth of the reproductive organs and fetus, as well as increased blood volume and water retention. Anywhere from 5 pounds (2.3 kg) to over 100 pounds (45 kg) can be gained during pregnancy. In America, the doctor-recommended weight gain range is 25 pounds (11 kg) to 35 pounds (16 kg), less if the woman is overweight, more (up to 40 pounds (18 kg)) if the woman is underweight.

Other physical changes during pregnancy include breasts increasing two cup sizes. Also areas of the body such as the forehead and cheeks (known as the 'mask of pregnancy') become darker due to the increase of melanin being produced.

The female body experiences many changes as the fetus grows through each trimester as shown and discussed in this pregnancy video. Two women at different stages in their pregnancy illustrate what has happened to their bodies.

Musculoskeletal changes

The body's posture changes as the pregnancy progresses. The pelvis tilts and the back arches to help keep balance. Poor posture occurs naturally from the stretching of the woman's abdominal muscles as the fetus grows. These muscles are less able to contract and keep the lower back in proper alignment. The pregnant woman has a different pattern of gait. The step lengthens as the pregnancy progresses, due to weight gain and changes in posture. On average, a woman's foot can grow by a half size or more during pregnancy. In addition, the increased body weight of pregnancy, fluid retention, and weight gain lowers the arches of the foot, further adding to the foot's length and width. The influences of increased hormones such as estrogen and relaxin initiate the remodeling of soft tissues, cartilage and ligaments. Certain skeletal joints such as the symphysis pubis and sacroiliac widen or have increased laxity.