Your Pregnancy Week by Week: Weeks 17-20

Medically Reviewed by Traci C. Johnson, MD on July 16, 2023
5 min read

Baby: Your baby now has doubled in weight in the last two weeks. Fat begins to form, helping your baby's heat production and metabolism. The lungs are beginning to exhale amniotic fluid, and the circulatory and urinary systems are working. Hair on the head, eyebrows, and eyelashes are filling in. Your baby makes fists and puts their little hands to their mouth. Their heart beats strong, pumping 100 pints of blood a day. Your active little one is doing flips and rolling around! Head to heel, your little sprout is the length of an asparagus spear -- 7.75 inches.

Mom-to-be: You're showing more now, with a typical weight gain of 5-10 pounds. You may also be noticing that your appetite has grown. As your uterus grows, you may find it harder to sleep comfortably. You may start to feel your baby move if it's not your first pregnancy. Weight gain, swelling, and hormones can make your feet expand. You may have more energy and feel your best these next couple of weeks.

Tip of the Week: To avoid feeling dizzy or faint, change positions slowly, especially when you move from a lying down position to sitting or from a sitting position to standing. If you feel lightheaded, sit down and lower your head, or lie down for a moment.


Baby: Your baby's rapid growth spurt is tapering off, but reflexes are kicking in. The baby can yawn, stretch, and make facial expressions, even frown. Taste buds are beginning to develop and can distinguish sweet from bitter. The baby will suck if its lips are stroked, and it can swallow and even get the hiccups. The retinas have become sensitive to light, so if a bright light is shined on your abdomen, your baby will probably move to shield its eyes. Little ears are working -- your baby can now hear sounds!

Mom-to-be: Your uterus, about the size of a cantaloupe, can probably be felt just below your navel. A mid-pregnancy ultrasound may be performed between now and 22 weeks to assess the baby's growth and development and to verify the due date. If the baby is in the right position, the ultrasound may show whether it's a boy or a girl. Your heart has to work 40% to 50% harder now to support your pregnancy. You may notice more low back pain, especially at the end of the day. Your doctor may do a vaginal ultrasound to check on your cervical length and the location of your placenta. You may notice a dark line running from your belly button to your pubic area. Circulation changes can make you feel dizzy, so stand up slowly.

Tip of the Week: Could your partner go with you for the ultrasound? It's a chance to catch the first glimpse of your baby together.

Baby: Your baby's skin is developing and transparent, appearing red because blood vessels are visible through it. The main airways of your baby's lungs, called the bronchioles, begin to develop. A creamy white protective coating, called vernix, begins to develop on the baby's skin. The next 3 weeks are the best time to see your baby's parts with ultrasound.  Your baby, from head to heel, is the same length as an eggplant -- 9.25 inches.

Mom-to-be: You may start to feel kicks, especially if this is not your first baby. As your baby continues to grow, you may be feeling some mid-pregnancy aches and pains by now -- lower abdominal achiness, dizziness, heartburn, constipation, leg cramps, mild swelling of ankles and feet, and a backache. Dilated blood vessels might cause tiny, temporary red marks (called spider nevi) on your face, shoulders, and arms. Swelling of your mucous membranes may cause congestion and nosebleeds. In most cases, your nausea and vomiting have tapered off.

Tip of the Week: Take care of yourself! Try not to get overtired while the baby is growing so quickly.

Baby: Your baby can hear sounds by now -- your voice, heart, and your stomach growling, as well as sounds outside your body. The baby will cover its ears with its hands if a loud sound is made near you, and it may even become startled and "jump." The baby is moving often, too -- twisting, turning, wiggling, punching and kicking. If you're having twins, they're almost constantly stimulating each other to move. Your baby sleeps now and can be awakened by noise and movement. At this age, your baby loves to put feet and toes in their mouth! From head to heel, your baby is the length as a papaya -- 10 inches.

Mom-to-be: Congratulations! You're near the midpoint of your pregnancy. Your uterus is just about even with your navel. If you're having twins, it may be about an inch above that. Your waistline has pretty much disappeared. You have likely gained about 33% of your pregnancy weight. Bladder infections are more likely because certain muscles in the urinary tract relax. You may want to start Kegel exercises to help with bladder control. Your breathing will deepen and you may sweat more than usual because your thyroid gland is more active. Your blood volume may have increased 70% by now.

Tip of the Week: Backache? Watch your posture. Sit with a footstool or use an ergonomic chair, avoid standing for too long, sleep with a small pillow under your side at the waist, and lift things with your legs instead of your back.

Hair is beginning to grow on your baby's head, and lanugo, a soft fine hair, covers their shoulders, back, and temples. This hair protects your baby and is usually shed at the end of the baby's first week of life.

Your baby's skin is covered with a whitish coating called vernix caseosa. This "cheesy" substance, thought to protect baby's skin from long exposure to the amniotic fluid, is shed just before birth.

You may begin to feel your baby move because they are developing muscles and exercising them. That movement is called quickening.