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A Guide to the Second Trimester of Pregnancy

A Guide to the Second Trimester of Pregnancy

You made it through the first trimester of pregnancy! Just a few months ago, your baby was a zygote, then an embryo, and now a fetus with distinct features. Let’s explore what’s happening with your baby and your body during the middle phase of pregnancy.

When does the second trimester start?

The second trimester of your pregnancy starts about week 13 or 14, around the beginning of your fourth month. It lasts about 14 weeks long, spanning months four, five, and six; ending on week 27.

Growth of baby in the second trimester

Pregnancy weeks 13-16

  • Your baby at week 13 is approximately the size of a lemon and will finish week 16 around the size of an avocado.
  • Vocal cords and mouth muscles are developing and getting ready for all those smiles, giggles, and first words.
  • The eyes are still developing and able to move, but eyelids are closed to protect them.
  • The head is still the largest part of the body.
  • Their bones, spine, and muscles are getting larger and stronger.
  • Your baby is producing urine which is being released into the amniotic fluid.
  • Their little limbs are growing! Your baby may start to move as they become more coordinated, but the movements are slight, so you may have to wait a few weeks to feel them.
  • Start singing those sweet lullabies. Around week 16, your baby may begin detecting some sounds from their tiny, still-developing ears.

Pregnancy weeks 17-20

  • By week 20, the pregnancy halfway mark, your baby will reach the size of a sweet potato.
  • That little heart is now pumping enough that you may be able to hear it through a specialized stethoscope.
  • A protective white, waxy moisturizing substance called vernix caseosa will start to cover your baby to safeguard their delicate skin.
  • Baby’s previously soft bones are beginning to harden.
  • Your baby is on the move, and you may start feeling those incredible first fluttering sensations known as “quickening.”
  • Get ready for that gender reveal. If you have an ultrasound around week 18, you may be able to determine your baby’s sex.

Pregnancy weeks 21-24

  • During these four weeks, your baby will grow from the size of a banana to a papaya. Notice a sudden growth spurt in your baby’s length? That may be because your doctor will start measuring your baby’s length from the crown (the top of the head) to the heel instead of the previous crown to rump.
  • Your tiny tenant may be moving, turning, twisting, and kicking harder than before.
  • By 24 weeks, your baby’s face is almost fully developed. They’re starting to look more like a newborn, complete with eyelashes, eyebrows, and hair.
  • Footprints and fingerprints have formed.
  • Lanugo, a fine, downy hair, covers the body. This unpigmented hair, which typically disappears before or shortly after birth, combines with the vernix caseosa to help protect the baby’s skin from anything damaging in the amniotic fluid.1
  • The lungs are formed but still developing. At this stage it is normal for them to still be filled with amniotic fluid.

Pregnancy weeks 25-27

  • Your baby is gaining about 6 ounces a week and growing like a weed, or in veggie terms, they’re going from cauliflower to cabbage-sized.
  • Taste buds have formed, and since you’re eating for two, your little one can taste what you eat!
  • The liver, lungs, and immune system are continuing to develop.
  • Their eyes will start to open and blink! Did they get mom or dad’s color eyes? Time will tell–a baby’s final eye color may not be established until months after birth.

Second trimester body changes

Many women and doctors believe that the second trimester is the most physically pleasant of the trimesters. While morning sickness is hopefully in the rearview mirror and you may feel more energetic, you’ll experience plenty of other changes.

Second trimester experiences and body changes

  • Get ready for that pregnancy pop. Your beautiful baby bump will begin showing, if it wasn’t already.
  • Fetal movement is going strong. Your baby’s getting busy, and you should feel the action as they kick, pedal, and make their way around the womb.
  • You may need to pee more often as your uterus gets bigger and puts pressure on your bladder.
  • Your hair and nails may be growing faster.
  • Hormones may be slowing down your digestive tract, some women may also experience constipation or hemorrhoids.
  • You may have a thin, whitish vaginal discharge that increases throughout your pregnancy.
  • Calf muscles, feet, or both may cramp up. Wearing comfy, supportive shoes, staying active, and keeping well-hydrated may help provide some relief.
  • Water retention and your increased blood volume may cause ankle and foot swelling.
  • Pregnancy brain is real and can make some women feel feel clumsy or forgetful. Experts aren’t entirely sure of its cause (leading theories link it to hormones, stress, and fatigue), but fortunately, it’s a temporary concern.
  • If you’re experiencing mild contractions toward the end of your second trimester, they're likely Braxton Hicks contractions. They can last up to two minutes and are generally harmless, but don’t hesitate to reach out to your doctor if you have concerns.

Second trimester pregnancy checklist

You’ve reached the halfway mark of your magnificent journey to motherhood. Here are some to-dos to tackle during this exciting stage.

Stay focused on nutrition. Your baby is counting on you for the calories and nutrients they need to grow and develop. Along with a healthy, well-balanced diet, keep taking prenatal vitamins and supplements that have the expert-recommended amounts of folic acid, DHA, iron, vitamin C, and other good-for-you vitamins and nutrients. Check out our pregnancy nutrition guide for more healthy tips.

Think about your maternity leave. Share your pregnancy news with your employer and explore your maternity leave options. Find out if your company is required to offer Family and Medical Leave Act (FMLA) leave and if you are entitled to any paid time off. 

Exercise. Moving is good for your overall wellness and can help relieve stress. The American Pregnancy Association recommends a minimum of 150 minutes of moderate-intensity aerobic activity every week, as long as you get your obstetrician’s OK.2 Avoid activities such as contact sports or those that require balance like skiing.

Rest and relax. Sleep contributes to you and your baby’s health, so feel free to nap whenever you’re feeling tired and prioritize getting plenty of sleep if you can.

Stay hydrated. Your body is busy producing extra blood, forming amniotic fluid, and carrying nutrients to your bundle of joy. That requires more water, so keep drinking that H2O. Water also helps flush out waste and can help you avoid constipation and dehydration.

Shop for maternity clothes. While you may be trying to hold out on buying a new wardrobe, you’ll be more comfortable with a few key maternity pieces.

Prepare for the big day. Many moms like to visit the hospital and tour the maternity ward to help mentally prepare for the big day. Birth classes can also provide a lot of helpful guidance and a chance to talk through any concerns with someone who has a lot of experience.

See your dentist. Those pregnancy-related hormonal changes can increase the likelihood of periodontal disease and dry mouth, so maintaining good oral health habits and regular dental cleanings can be a great thing to keep in mind during this time. Most dental procedures are considered safe during pregnancy. In fact, the second trimester is considered an ideal time for dental work.3 If you put it off until the third trimester, you may find lying on your back in the dental chair more uncomfortable.

Join Enfamil Family Beginnings

You’re cruising through your second trimester and your cute cuddlebug will be here before you know it. Start preparing for all the amazing changes pregnancy and parenthood will bring with Enfamil Family Beginnings. It’s the perfect resource for new and expecting moms. Save on Enfamil products, track your bump and baby’s growth, and get helpful articles each week relevant to your journey. Join now.






All information on, including but not limited to information about health, medical conditions, and nutrition, is intended for your general knowledge. It is not a substitute for a healthcare professional's medical identification, advice, or management for specific medical conditions. You should seek medical care and consult your doctor, OB-GYN, or pediatrician for any specific health or nutrition issues. Never disregard professional medical advice or delay seeking medical care because of something you have read on


All information on Enfamil, including but not limited to information about health, medical conditions, and nutrition, is intended for your general knowledge and is not a substitute for a healthcare professional's medical identification, advice, or management for specific medical conditions. You should seek medical care and consult your doctor or pediatrician for any specific health or nutrition issues. Never disregard professional medical advice or delay seeking medical treatment, care, or help because of information you have read on Enfamil.