Yours and Baby's Changes, 37-40 Weeks


Your baby is now fully developed. The skin is smooth and whitish to bluish-pink in color. The body becomes plump as weight increases. Fingernails may grow beyond the fingertips. The bones of the skull are firm and bones in the rest of the body continue to grow. Many reflexes are developed.

The bones of the skull are firm, while bones in the rest of the body continue to grow. The internal organs and systems are mature, and fine lanugo hairs have almost disappeared. The baby continues to gain weight, making the skin smoother. Nails now grow beyond the tips of fingers and toes. The reflexes needed for survival (crying, sucking, rooting, etc.) are well developed. And, if your baby is a little boy, his testicles have descended into his scrotum.

Depending upon the baby's race, skin tone will vary from white to pink to bluish-pink. Melanin, the pigment that colors the skin, is produced only after exposure to light.

At full term, defined as 38 to 42 weeks of pregnancy, baby's immune system is generally mature enough to combat minor infections, and has passive immunity to diseases for which you have developed antibodies, such as measles, mumps, and chickenpox. Because this immunity is "borrowed" from you and therefore is not permanent, it will be very important for you to discuss immunization with your pediatrician.


You've now reached the final stages of your pregnancy. You may notice that the baby has moved downward in your abdomen (lightening). If you've already had a baby, lightening may not occur before labor begins. Due to the new positioning of the baby you will be able to breathe more easily, however, you may also need to urinate more often. You may experience more frequent contractions.

Even though the end is in sight (and, you may be thinking, "none too soon!"), your body is continuing to make important adjustments for your baby's arrival. At the same time, your baby continues to grow to be ready for life in the outside world.

By now your baby may have "dropped" or moved lower in your abdomen into your pelvis. Also call lightening, this downward movement may not occur until labor if you've had baby before. While this shift in the baby's position usually makes breathing easier, it can cause you to need to urinate more frequently. Lightening brings other physical changes, as well. The fundal height (height of the growing uterus) will decrease, while pelvic pressure, leg cramps, and edema are likely to increase. This is all due to the pressure caused by the shift in the baby's position in preparation for the birth process. You also may be experiencing more frequent contractions at this time.

Reprinted with permission from Her Healthcare.