A Week By Week Look At Your Pregnancy’s Second Trimester


Published: January 27, 2015

Second Trimester

Congratulations! You’ve made it to your second trimester of pregnancy, about 14 to 27 weeks. You’re probably feeling much better physically, and can even enjoy being pregnant. Your enlarging uterus and larger breasts make the pregnancy more “real” to you, unlike the vague, abstract notion of pregnancy which many women have during the first trimester. It’s in the second trimester, 20 weeks, that you’ll reach the halfway point in your pregnancy.

It’s important to continue your prenatal care. Your blood pressure and weight will be checked at every visit to your health care provider. It’s possible, also, to monitor the baby’s wellbeing.

Tracking baby’s growth becomes easier. The top of the uterus can be felt through the abdominal wall. By measuring from the top of the uterus to the pubic bone, your healthcare provider can determine if the baby is growing at a normal rate.

Listening to your baby’s heartbeat will occur at every prenatal care visit, using an instrument that detects motion and transmits it as sound.

Assessing the baby’s movement is also an indicator of the baby’s wellbeing. Your healthcare provider will want to know when you notice flutters or kicks. It usually occurs by 20 weeks – the halfway mark of the pregnancy, or earlier, if you’ve been pregnant before.

Laboratory tests may be performed to check for low iron levels, possibly anemia, or for gestational diabetes, a type of diabetes that can develop during pregnancy.

If you have Rh-negative blood, an inherited trait which affects red blood cells, you may need a test for Rh antibodies. It can create a problem if the baby inherits Rh-positive blood. Without treatment, the antibodies could cross the placenta and attack the baby’s red blood cells, especially in a subsequent pregnancy with an Rh-positive baby.

A urine sample is usually tested at every visit, for signs of a bladder, urinary tract, or kidney infection.


Your Baby’s Development

13 Weeks: Your baby’s intestines, growing outside the baby’s abdomen earlier in pregnancy become enclosed by the abdomen. The baby produces urine, which it releases into the amniotic fluid. Tissue that will become bone develops around the baby’s head and within the arms and legs.

14 Weeks: The baby’s arms reach the length they will be relative to other body structures, and the neck is better defined. Red blood cells are forming in your baby’s spleen. The baby’s gender becomes apparent this week or shortly after. Ovarian follicles begin to form in girls; the prostate gland appears in boys.

By this time your baby is about 3 ½ inches long from the top of the head (the crown) to the baby’s rump and weighs about 1 ½ ounces.

15 Weeks: The baby is growing rapidly, the skeleton is developing bones, which can soon be seen on ultrasound. Scalp hair is forming a pattern.

16 Weeks: Your baby’s eyes, at the beginning on the sides of the head, begin to face forward, slowing moving around the head. The ears are close to reaching their final position. Your baby may be making sucking motions with his or her mouth. The baby’s movements are becoming coordinated and can be detected during ultrasound examinations.

At this time your baby is more than 4 ½ inches long from crown to rump.

17 Weeks: Fat stores begin to form underneath the baby’s skin. The fat will provide energy and help keep your warm after birth.

18 Weeks: Your baby’s ears stand out from the side of the head; (s)he may begin to hear.

19 Weeks: A greasy, cheese-like coating called vernix caseosa begins to cover the baby. It helps to protect the baby’s skin from abrasions and chapping that can result from exposure to amniotic fluid. In girls, the uterus and vagina begin to form.

By now, the baby is about 6 1/3 inches long, from crown to rump.

21 Weeks: Your baby is more active, and able to swallow. It’s time for the baby to gain weight more quickly.

24 Weeks: Your baby is sleeping and waking regularly. Taste buds form, as do fingerprints and footprints. In boys, the testes descend from the abdomen. In girls, the uterus and ovaries are in place, complete with a lifetime supply of eggs.

27 Weeks: Your baby might be able to respond to familiar sounds, such as your voice. The lungs are producing surfactant – the substance that will allow the lungs to inflate after birth.

All the baby’s organs are growing and maturing. Your baby is about nine inches long and weighs nearly two pounds. This marks the end of the second trimester.

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About Faith A. Coleman, MD

Dr. Coleman is a graduate of the University of New Mexico School of Medicine, and holds a BA in journalism from UNM. She completed her family practice residency at Wm. Beaumont Hospital, Troy and Royal Oak, MI, consistently ranked among the United States Top 100 Hospitals by US News and World Report. Her experience includes faculty appointments to a family practice residency and three medical schools, as well as Director of Women's and Children's Health Promotion Programs with the NE Texas Public Health District.

Dr. Coleman is the Expert on Gifted Children for the New York Times, parenting writer for Demand Media Studios, as well as health and medical writer for several online information services. She writes professional management material for health care providers and about the personal experience of being a physician. Faith treasures most the role of mother. Her passions include the well-being and education of children and families. She doesn't tweet, but welcomes email: facoleman8889@yahoo.com.

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