Pregnancy: Second Trimester

Information on what you can expect during months 4-6 of your pregnancy.

Most women find the second trimester of pregnancy easier than the first. You might notice that symptoms like morning sickness and fatigue are going away, but other changes to your body are occurring. Your abdomen will expand as you gain weight and the baby continues to grow. Many of the aches and pains you had in the first trimester may continue.

The following has been adapted from the National Women's Health Information Center website.

Some of the following aches and pains may make their first appearance during the second trimester:

• Pain in the abdomen, groin, and thighs
• Backaches
• Shortness of breath
• Weight gain of about one pound per week, or about three to four pounds per month during the second trimester.
• Stretch marks and other skin changes
• Tingling in hands and fingers
• Itching on the abdomen, palms, and soles of the feet

Changes in Your Baby

By the end of the second trimester your baby will weigh about 1 3/4 pounds and be about 13 inches long. Fingers, toes, eyelashes, and eyebrows begin to develop. Around the fifth month you might feel your baby move and by the end of the second trimester all of your baby's essential organs like the heart, lungs, and kidneys are formed.

During the second trimester, you should continue to see your doctor for prenatal care.  Most pregnant women have monthly office visits with their doctor or midwife until the end of this trimester.

During the second trimester your doctor can use an ultrasound to see if your baby is developing in a healthy way. You will also be offered prenatal and screening tests to look for genetic birth defects. Some of the diagnostic and screening tests your doctor might suggest in the second trimester include:

Amniocentesis

Amniocentesis is usually not done until you are at least 16 weeks into your pregnancy. With an amniocentesis your health care provider inserts a thin needle through your abdomen, into your uterus, and into the amniotic sac to take out a small amount of amniotic fluid for testing.

Chorionic villus sampling (CVS)

This test is performed between 10-12 weeks of pregnancy. Your health care provider inserts a needle through your abdomen or inserts a catheter through your cervix in order to reach the placenta. Your doctor then takes a sample of cells from the placenta. This test cannot find out whether your baby has open neural tube defects.

Maternal serum screening test

This blood test is called by many different names including multiple marker screening test, triple test, and quad screen.  It is typically done between 15-20 weeks of pregnancy. It checks for birth defects such as Down syndrome, trisomy 18, or open neural tube defects.

Ultrasound

The best time to get a targeted ultrasound is between 18-20 weeks of pregnancy. Most major problems with the way your baby is formed can be seen at this time.

The following has been adapted  from  the Mayo Clinic website.

Week 13: Baby flexes and kicks

You can not feel it yet, but your baby can move in a jerky fashion by flexing the arms and kicking the legs. This week, your baby might even be able to put a thumb in his or her mouth.  Your baby's eyelids are fused together to protect his or her developing eyes. Tissue that will become bone is developing around your baby's head and within the arms and legs. Tiny ribs may soon appear.

Week 14: Hormones gear up

The effect of hormones becomes apparent this week. For boys, the prostate gland is developing. For girls, the ovaries move from the abdomen into the pelvis. Meconium, which will become your baby's first bowel movement typically occurring after the baby's birth, is made in your baby's intestinal tract. The roof of your baby's mouth will be completely formed.

Week 15: Skin begins to form

Your baby's skin starts out nearly transparent. Eyebrows and scalp hair appear.  Your baby's eyes and ears now have a baby-like appearance and the ears have almost reached their final position.

Week 16: Facial expressions are possible

Your baby is 4-5 inches long and weighs a bit less than 3 ounces. Your baby's eyes are becoming sensitive to light.  Facial muscles continue to develop.  Your baby may have frequent bouts of hiccups. If the baby is a girl, millions of eggs are forming in the baby's ovaries.

Week 17: Fat accumulates

Fat stores begin to develop under your baby's skin this week. The fat will provide energy and help keep your baby warm after birth.

Week 18: Baby begins to hear

As the nerve endings from your baby's brain "hook up" to the ears, your baby may hear your heart beating, your stomach rumbling or blood moving through the umbilical cord. He or she may even be startled by loud noises. Your baby can now swallow.

Week 19: Lanugo covers baby's skin

Your baby's delicate skin is now protected with a pasty white coating called vernix. Under the vernix, a fine, down-like hair called lanugo covers your baby's body.  Your baby's kidneys are already producing urine. The urine is excreted into the amniotic sac, which surrounds and protects your baby. Your baby can make reflexive muscle movements and if you have not felt movement yet, you will soon.

Week 20: The halfway point

Halfway into your pregnancy, your baby is about 6 inches long and weighs a little over half a pound. Under the protection of the vernix, your baby's skin is thickening and developing layers. Your baby now has thin eyebrows, hair on the scalp and well-developed limbs.

Week 21: Nourishment evolves

your baby begins to absorb small amounts of sugar from swallowed amniotic fluid and your baby's bone marrow starts making blood cells.

Week 22: Taste buds develop

Your baby weighs in at about 1 pound.  Taste buds are starting to form and your baby's brain and nerve endings can process the sensation of touch. If your baby is a boy, the testes begin to descend from the abdomen and for girls, the uterus and ovaries are in place.

Week 23: Lungs prepare for life outside the womb

Your baby's lungs are beginning to produce surfactant, the substance that allows the air sacs in the lungs to inflate.  Your baby will begin to look more like a newborn as the skin becomes less transparent and fat production increases.  With intensive medical care, some babies born at 23 weeks can survive.

Week 24: Sense of balance develops

Your baby weighs about 1 1/2 pounds. Footprints and fingerprints are forming.   You may notice a regular sleeping and waking cycle.  Babies born at 24 weeks have more than a 50% chance of survival with the chance of survival increasing with every passing week.

Week 25: Exploration continues

Your baby's hands are now fully developed, Exploring the structures inside your uterus may become the baby's main activity.

Week 26: Eyes remain closed

Your baby weighs between 1 1/2- 2 pounds. The eyebrows and eyelashes are well formed, and the hair on your baby's head is longer and more plentiful. Although your baby's eyes are fully developed, they may not open for another two weeks.

Week 27: Second trimester ends

This week marks the end of the second trimester. Your baby's lungs, liver and immune system are continuing to mature.

Click on the highlighted links in this sentence for more information about the 1st trimester and the 3rd trimester of your pregnancy.