The second trimester of pregnancy spans from week 13 to week 27. This is when most women actually start to appear pregnant. By week 16, the top of your uterus (the fundus) will be about halfway between your pubic bone and your navel. During this time, many women feel better, both physically and emotionally. The worst of morning sickness has passed. The baby is growing, but hasn’t become large enough to crowd your organs. Overall, it’s a time when women often feel at their best during pregnancy, as major changes – both to their body and their baby – are just around the corner.
The second trimester.
What To Expect
Weight gain. Your uterus is becoming heavier as it expands to make room for your growing baby. Expect your abdomen to grow – and your breasts, too. In addition to growth due to stimulation from estrogen and progesterone, fat may also accumulate in your breasts. At this point in your pregnancy, a supportive bra is something you’ll definitely want to invest in. You may gain up to four pounds a month from this point forward, until the end of your pregnancy.
Skin changes. Some areas of your skin may become darker as blood circulation to it increases – particularly the area around your nipples, sections of your face, and the line that runs from your navel to your pubic bone. You may also start to notice stretch marks along your stomach, breasts, arms, and thighs during the second trimester. If they become itchy, treat them with a simple moisturizer. Stretch marks are a necessary evil of pregnancy, but don’t fret too much – they usually fade in appearance over time.
Braxton Hicks contractions. Your uterus has a lot of work ahead of it. One way it prepares for it is by conducting warm-up contractions of sorts. These are known as Braxton Hicks contractions. You’ll typically feel them in your lower abdomen and groin areas. They’ll come and go with little warning, so don’t be alarmed. But call your doctor if they become painful, or occur with alarming frequency.
Nasal and gum issues. During pregnancy, more blood flows through the mucus membranes, which causes the lining of your airways to swell. This can lead to snoring, congestion, nosebleeds, and softening of the gums. Switching to a softer toothbrush may help reduce any irritation you might experience due to this totally natural change.
Your Baby's Development
During the second trimester, many mothers experience a heightened sense of the reality of their new baby’s life. You’ve heard the baby’s heartbeat at prenatal appointments, and maybe have even seen it move. And for the first time in your pregnancy, you’ve been forced to forgo your usual wardrobe for maternity clothes. Most exciting of all, your baby is developing at a rapid rate.
Week 13: Tissue that will eventually become bone is forming around your baby’s head, and inside his or her arms and legs. The baby is also able to form urine at this point, which it discharges into the amniotic fluid.
Week 14: The baby’s arms have almost reached the length they’ll be at the time of birth. And the gender of the baby may also become apparent this week.
Week 15: Now, the baby’s skeleton is rapidly developing, forming bones. Also, his or her hair pattern is forming.
Week 16: Your little one has now reached approximately 4.5 inches in length, and weighs about 3.5 ounces. The facial muscles have developed to where the baby can now make expressions, squinting and frowning.
Week 17: As the baby continues to grow, important stores of fat are accumulating underneath its skin. This will give it energy and keep it warm upon its welcome to the world.
Week 18: As the nerve endings from the brain connect to the baby’s ears, it develops the ability to hear. Outside sounds may even startle him or her, prompting movement.
Week 19: In spite of the amniotic fluid around your baby’s ears, he or she may be able to pick up on your voice during conversations at this point. Also, if it’s a girl, her uterus is now forming.
Week 20: Congratulations – you’ve reached the halfway point of your pregnancy! Now you’re more likely to feel your baby’s movements, and you may even be aware of its sleep/wake cycles. The baby is now coated in a creamy white substance called vernix, which protects its skin.
Week 21: Your baby, which continues to grow and remain active in the amniotic fluid, now weighs approximately 13 ounces – nearly a pound!
Week 22: This week, your baby has developed eyebrows. It is also covered in a down-like hair called lanugo, which holds the protective vernix on the skin.
Week 23: The eyes of the baby become very active at this point in the pregnancy, moving rapidly. The fingerprints and footprints are forming, and soon, the tongue will develop tastebuds.
Week 24: By this time, real hair is beginning to grow on your baby’s head. Babies born at this point have some chance at survival, with very special care.
Week 25: Now that your baby’s hands are fully developed, it will begin to use them to explore the inside of your uterus. However, it has limited feeling since the nerve connections to the hands are far from fully developed.
Week 26: Now, the lungs of the baby are producing surfactant, which allows the air sacs in the lungs to inflate and keeps them from sticking together and collapsing during deflation. Also, your baby has fully formed fingernails.
Week 27: Now that you’ve reached the end of the second trimester, your baby has nearly tripled in size since the 12-week mark. Still, its lungs, liver, and immune system have a long way to go. Indeed, much excitement awaits in the third – and final – trimester.
Tests and Screenings
During the second trimester, you’ll visit the doctor regularly – probably about once a month – for prenatal care. You’ll undergo routine lab tests, and the doctor will measure your baby’s growth and assess its development.
Fetal movement assessment. Around the 20-week mark, you’ll begin to feel your baby move inside your uterus as it kicks or flutters. Tell your doctor when you notice these movements. The doctor may also use a Doppler instrument that detects motion – even though your baby makes no actual noise when it moves.
Lab tests. You will be subject to routine lab tests during the second trimester. Your doctor may take a urine sample to test your sugar and protein levels. You may need blood tests to check for gestational diabetes or iron deficiencies. If you have Rh negative blood, you may be tested for antibodies, which can be harmful to your baby if he or she has Rh positive blood. Blood tests may also be conducted to screen for developmental or chromosomal disorders, such as Down syndrome.
Ultrasound and diagnostic tests. An ultrasound continues to be an important way for your doctor to assess the health and development of your baby. And it also allows you to “see” your baby as it grows. If the results of a blood test or an ultrasound indicate a problem of any kind, your doctor may recommend a more invasive diagnostic test, such as amniocentesis – also known as an amniotic fluid test (AFT). Women aged 35 and older are more likely to undergo such tests, although less invasive alternatives are often tried first.