Pregnancy by Week: Second Trimester (Weeks 13-26)

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Baby's Growth & Development

During your second trimester, baby's toenails, eyebrows and hair are starting to grow and teeth are forming under the gums. Your baby is able to kick and turn over. You may feel the baby moving and be able to tell when they're sleeping or moving. Hair starts to grown on the head and downy hair, called lanugo starts to cover the baby's body. Your baby will also begin reacting to sound. 

  • Week 13 - Your baby's hands have 27 bones connected by ligaments, which are structurally complete. The feet, with separated toes and developed heels, are also nearly formed. Fetal development parallels the developmental stages of infancy. Because your baby will use his hands before he walks on his feet, hands develop earlier in utero than feet do. Your baby can suck her thumb, strengthening and filling out the cheek and jaw muscles.
  • Week 14 - Your baby's eyes have moved forward and ears have moved upward on the head. The neck is straighter and strong, and the head is able to turn. Now your baby can move around in her amniotic bath, although you cannot yet feel these movements.
  • Week 15 - This month your baby will double in length to six inches in a sitting position and quadruple its weight from 1-4 oz. The curled fetus now begins to straighten out, as the back grows stronger and the head becomes proportionally smaller than the rapidly lengthening body.
  • Week 16 - In the second trimester, your baby's fetal brain develops folds on its surface, signaling the advancement of its many regions, especially in the forebrain that controls the intellect, motor control and memory. Brain development continues years after birth. The fingertips already have ridged patterns unique to each baby. Even identical twins have different patterns.
  • Week 17 - By the middle of the second trimester, your baby is about eight inches long and weighs half a pound. Your baby's bones are hard and the joints flexible. Now you can feel the baby's kicks and rolls. Even hiccups can be felt on occasion. Eyelashes begin to appear.
  • Week 18 - Your baby's heart pumps 144 liters of blood a day, creating enough percussion to be heard faintly through a stethoscope. Your baby's skin is loose and wrinkled, without yet a layer of fat underneath.
  • Week 19 - Your baby begins secreting vernix, the waxy coating that protects the skin from the amniotic fluid and cushions it against scratches from its own toes and fingers as it kicks and rolls. Newborns arrive coated in vernix, which is cleaned off immediately after delivery. Your baby's circulatory system is fully functional, as the umbilical cord thickens to carry liters of blood and nourishment daily from you to the baby.
  • Week 20 - Your baby is approximately 10 inches long and weighs 12 ounces. Your baby moves around a lot, but you will just begin to feel faint movements called "quickening" and maybe some hiccups, small spasms or twitching in the lower abdomen. Your baby's brain is beginning to grow rapidly during this week. If the fetus is a girl, her uterus has completely formed. If a boy, his testes will begin to descend. The hair on the baby's head is starting to appear.
  • Week 21 - Though your baby has no body fat at this point, it will gain more weight in the next few weeks, and by week 25, it will weigh almost twice as much. The motions, or "quickening," are increased leg and arm activity because of muscular development. Your baby's respiratory system is still immature and requires much more development. As your baby swallows amniotic fluid, its body will absorb the water from the fluid and the rest will go into its large bowel.
  • Week 22 - Your baby is approximately 10-11 inches from crown to rump and weighs 15 ounces. Though you are aware of your baby's movements, it may be a few weeks before someone else can feel these movements by putting a hand on your abdomen. Your baby is most active in the early mornings and after a nightly meal. The sugar content in some foods usually gets her moving! Your baby is growing steadily and will gain more than six ounces this week.
  • Week 23 - Blood vessels develop in his lungs, and her plugged nostrils begin to open. By this week, his hearing will be developed enough to respond to outside sounds and voices, and she may jump at sudden noises. Capillaries are starting to develop underneath her skin, giving her a more pinkish color. Her hiccups will become stronger and more frequent in the coming weeks. They do not bother him in any way or cause her discomfort.
  • Week 24 - Your baby is approximately 12-13 inches long and weighs 1.25-1.5 pounds. She still has no fat on her body yet, but her arm and leg muscles are well developed. Her eyelids are sealed, but she makes facial expressions: frowning, squinting, and pursing her lips. Her nostrils are opening and preparing to draw air into her lungs. The alveoli ("air sacs") in the lungs are forming, but not enough that she can breathe outside the womb.
  • Week 25 - Your baby will grow rapidly during this week and gain about half a pound. His brain and nervous system continue their rapid growth as they become more complex. By this time, rapid bone formation is occurring, requiring more calcium for bone development, especially during the third trimester. She is making breathing movements, but she would not be able to fully take in air at this point.
  • Week 26 - Your baby is approximately 14 inches long and weighs 2-2.5 pounds. Babies will kick most frequently in the seventh month, usually at night and early morning. Her eyelids have opened. Her lungs are capable of breathing in air. The alveoli begin secreting "surfactant," which keeps them from collapsing. At this point, she is only taking in small breaths of fluid in the womb, but she could survive and breathe outside the womb with medical assistance.

First Baby Movements

  • felt between 18-22 weeks of pregnancy, may be as early as 14 weeks
  • feels like a flutter, bump or nudge
  • you may think they are gas pains or hunger pains
  • if the baby's movements are not felt a day or two do not worry your baby may have changed the way it is laying and you simply may not feel the kicks
  • as long as your provider can hear the baby's heartbeat, all is welllater in pregnancy the baby's movements are more able to predict, and we can tell more about how the baby is doing by this motion
  • enjoy the baby's tiny movements when you feel them

Your Body

You start to "show". Your clothing may no longer fit. Don't think that you are fat. You are pregnant!

  • blood supply will rise from 3 ½ quarts to 5 ½ quarts by the end of your pregnancy
  • you may be less tired and start to enjoy being pregnant
  • you may be hungry more often and may feel cravings for some foods
  • eat a well-balanced diet
  • drink at least six to eight glasses of water a day

Signs of early labor

  • Labor between 20 and 37 weeks of gestation
  • Your cervix softens and open earlier than normal and causes regular, often painful contractions
  • Premature labor can occur in any pregnancy and may occur without you knowing that your uterus is contracting or tightening

You should know the warning signs of preterm labor. Notify your health care provider as soon as you have these warning signs:

  • Menstrual-like cramps in the lower abdomen that comes and goes in a regular pattern or is constant.
  • Low, dull pain in your back that you feel below your waist that comes and goes in a regular pattern or is constant.
  • Pelvic pressure or intermittent pains that come and go in the lower abdomen which may feel like heaviness in your pelvis.
  • Cramping in your gut (intestinal) without diarrhea
  • Increase or change in vaginal discharge that becomes thicker (mucous-like), watery, or blood tinged.
  • Contractions - A contraction is a tightening of the uterus, which may be painless. Although you may feel contractions on occasion during pregnancy, frequent contractions (every 10 minutes lasting 1 minute) before 37 weeks' gestation may be the start of preterm labor and should never be ignored.

Difference between a True Contraction and Braxton-Hicks Contraction

A Braxton-Hicks Contraction

  • An overall tightness or slight cramping in your abdomen
  • May be felt very high up, or you may feel them across the middle
  • Often brought on by lots of motion or being active
  • May start out of nowhere, last a short time, and go away
  • No gradual increase or "peak" to them
  • Do not cause pain, just tightness
  • Tend to go away if you drink water or sit down for a while

A True Contraction

  • Feels very low, either in front or back, and sometimes wraps around
  • A strong tightness that grows in strength, peaks, and drops off again
  • Do not go away or change if you move around, sit down, or drink water

When to Call Your Provider

If you have contractions, pressure or cramping every 10 minutes or closer that continue for 2 hours, even though you have followed the previous directions. If you have other warning signs of preterm labor that do not go away after 1 hour of rest.

Round Ligament Pain

  • round ligament pain is a sharp pain or jabbing feeling often felt in the lower belly or groin on one or both sides
  • the pain should only last a few seconds
  • this pain may worry you, but it is normal as your baby grows and your body changes

Bleeding Gums

  • Your gums may become red, soft and more likely to bleed
  • use a soft toothbrush, mild toothpaste and floss gently
  • see a dentist if your gums become painful or swollen
  • it is a good idea to have your teeth and gums cleaned in a dentist office early in pregnancy and again before you have the baby

Nose Stuffiness & Nose Bleeds

  • it is normal for your nose and sinuses to feel stuffy while pregnant
  • it may feel like a lasting cold or allergy
  • there is no set treatment, an over the counter saline nose spray or drops may help


  • most women are able to work while pregnant
  • if you work, take frequent breaks when able
  • try not to stand or sit for a long time
  • try lying down for an hour when you get home
  • leave your household chores until after you have rested
  • this is a good time to let someone help you, if someone is able

Some things you do at your job may be harmful to an unborn baby:

  • working with lead or mercury; making paint, glass, batteries or ceramics; pottery glazing, printing
  • working with radiation in an industrial, health care, or dental setting

Talk to you employer if you believe you are risk.

Leg Cramps

Many women feel cramps in their calves and feet, mostly at night. When you get a cramp, stand up on a flat surface, and try walking or curling your toes to free the cramp. If the cramp does not let go and you have lasting pain in your leg, or you have swelling or redness, see your doctor as soon as you can.


Feeling faint is normal while pregnant.

  • it may be from staying in one place too long, or when you change from lying or sitting to standing up
  • when standing for a long time, bend your knees and move your legs often to increase blood flow
  • move slowly when changing places
  • sit with your head down or lie down on you left side when feeling faint
  • low blood sugar is one more rare cause for feeling light-headed or faint
  • always have breakfast; do not go too long between meals
  • carry small healthy snacks to eat, this may ease the faint feeling
  • high humidity, heat, and fluid loss can also make you feel faint
  • try not to get overheated; drink plenty of fluids when in a hot setting

If you do faint, call you doctor.


During the second trimester (14 to 27 weeks of pregnancy), a yellowish or whitish fluid called colostrum may leak from nipples; this is normal due to hormonal changes while pregnant.


  • Increase in size and become more firm and tender
  • The brownish area around the nipple (areola) becomes darker and you can see small bumps
  • Wear a supportive bra to ease the strain on your back
  • Breasts need no special care while pregnant
  • Nipple stimulation can cause uterine contractions and, at times lead to not normal contractions

Vaginal Discharge

  • Increased blood supply and hormones cause your birth canal to increase its normal secretions.
  • Due to body changes it may be easier for you to get yeast infections.
  • Since a whitish vaginal discharge is normal while pregnant, good self-care is important.
  • Keep your panties clean and dry. If needed, wear a panty liner.
  • Cotton panties or at least those with a cotton crotch are better than underpants made of man-made fiber.
  • You may bath or shower, but do not douche.
  • Report any vaginal discharge that looks yellow, greenish, thick and cheesy, or has a bad smell and you have pain, itching, or burning.

Weight Gain

While pregnant, a weight gain of 15 to 20 pounds is often healthy, unless your provider tell you not too. If you are eating healthy food, your gain is not fat. Most of this weight gain can be lost within three to six months after you give birth. Here's what the weight gain might include:

  • Baby..........................7.5 pounds
  • Placenta.....................1.5 pounds
  • Amniotic Fluid.............2.0 pounds
  • Breast tissue...............1.0 pounds
  • Womb........................2.5 pounds
  • Other fluids...............2.75 pounds
  • Other........................3.25 pounds
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Up Next: Third Trimester (week 27 - end of pregnancy)

Learn what happens during the third trimester of your pregnancy, including swelling, travel limits and labor warning signs.
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