The fifth month of pregnancy, roughly weeks 17 through 20, is when most parents feel their baby move for the first time and see detailed images of their growing child on ultrasound. It falls squarely in the second trimester, often called the most comfortable stretch of pregnancy. Your baby is developing functioning senses, growing protective coatings on their skin, and reaching about 10 inches in length by the end of the month.
What Your Baby Looks Like Now
At the start of month five, your baby is roughly the size of a pear. By week 20, they’ve grown to about the length of a banana. Their legs are lengthening quickly: the thighbone alone nearly doubles in size between weeks 17 and 20. Tiny fingernails and toenails are forming, and the face looks distinctly human, with eyebrows and eyelids now in place.
Two protective layers appear on your baby’s skin during this period. The first is lanugo, a coating of fine, soft, unpigmented hair. The second is vernix caseosa, a thick white substance that clings to the lanugo and shields delicate skin from the amniotic fluid surrounding it. Vernix prevents water loss, helps regulate temperature, and protects against irritants like urea and electrolytes in the fluid. Think of it as a built-in moisturizer and barrier suit that your baby will wear until birth.
Senses Starting to Come Online
Your baby’s taste buds are already considered functionally mature by around week 17. The fetus swallows amniotic fluid regularly, and that fluid contains glucose, fructose, fatty acids, and traces of whatever you eat. Research shows that fetuses actually swallow more frequently when the amniotic fluid tastes sweet and less when it tastes bitter. These are some of the earliest signs of flavor preference, and studies suggest babies remember these tastes after birth, responding differently to flavors they encountered in the womb.
Hearing is also developing during these weeks. The structures of the inner ear are maturing, and by the end of the fifth month your baby is beginning to respond to sound. Loud noises may even startle them. Light sensitivity is emerging too, though the eyelids remain fused shut for now.
Feeling Your Baby Move
One of the most anticipated milestones of month five is quickening, the moment you first feel your baby move. If this is your first pregnancy, you’ll typically notice it around week 20. If you’ve been pregnant before, you may pick it up as early as week 16, because you know what to look for.
The sensation doesn’t feel like a kick at first. Most women describe it as fluttering like a butterfly, tiny bubbles popping, light tapping, or small muscle spasms. It’s subtle enough that you might mistake it for gas or digestion in the early days. Over the coming weeks, those flutters strengthen into rolls and definite kicks. If you haven’t felt any movement by 24 weeks, it’s worth mentioning to your provider, but there’s a wide range of normal.
The 20-Week Anatomy Scan
The biggest medical appointment of month five is the anatomy scan, typically scheduled around week 20. This detailed ultrasound is more than a chance to see your baby. The sonographer will methodically examine your baby’s bones, heart, brain, spinal cord, face, kidneys, and abdomen. They’ll also check your placenta’s position and blood flow in your uterus.
The scan screens for 11 specific conditions, including spinal abnormalities like open spina bifida, serious heart defects, cleft lip and palate, and chromosomal conditions such as trisomy 18 and trisomy 13. Don’t be alarmed if the sonographer is quiet during the exam. They’re concentrating on detailed measurements. This is also the appointment where you can find out your baby’s sex, if you want to know.
Your Baby’s Digestive System
By the fifth month, your baby’s digestive tract is practicing for life outside the womb. The fetus swallows amniotic fluid, which passes through the stomach and intestines. This process helps the gut mature and begins forming meconium, the dark, sticky substance that will become your baby’s very first bowel movement after birth. Meconium is a mix of swallowed amniotic fluid, digestive secretions, and shed cells that accumulates in the intestines throughout the rest of pregnancy.
Changes in Your Body
By week 20, your uterus has risen to roughly the level of your belly button, and your pregnancy is clearly visible. Many of the rough first-trimester symptoms like nausea have faded, but a new set of physical changes takes their place. Heartburn and constipation are common as your growing uterus presses against your digestive organs. Shortness of breath can crop up as your body demands more oxygen. Some women notice nosebleeds and bleeding gums, both caused by increased blood volume stretching the tiny blood vessels in your nose and mouth.
Your breasts may have grown by as much as two cup sizes at this point, driven by hormonal changes preparing your body for milk production. Dizziness can happen if you stand up too quickly, since your cardiovascular system is working harder to circulate a much larger blood volume. You might also notice skin changes like a dark line running down your belly (linea nigra) or darker patches on your face.
Sleep and Comfort
As your belly grows through month five, sleeping on your back becomes less ideal. The weight of your uterus can press on a major blood vessel that returns blood to your heart, potentially reducing blood flow to the fetus and making you feel dizzy or lightheaded. The American College of Obstetricians and Gynecologists recommends sleeping on your side during the second and third trimesters. Keeping one or both knees bent helps, and placing a pillow between your knees and another under your belly can take pressure off your lower back. A full-length body pillow is another option many women find useful.
Nutrition in the Fifth Month
Your baby’s skeleton is hardening rapidly during month five, which means your calcium needs are high. If you don’t get enough calcium from food, your body will pull it from your own bones to supply the baby. Dairy products, fortified plant milks, leafy greens, and canned fish with soft bones (like sardines) are all good sources.
Iron is equally important. Your blood volume is expanding significantly, and iron is essential for making the extra red blood cells both you and your baby need. The World Health Organization recommends 30 to 60 milligrams of elemental iron daily during pregnancy to prevent anemia and reduce the risk of low birth weight and preterm delivery. Many prenatal vitamins cover this, but your provider may suggest additional supplementation if your levels are low. Pairing iron-rich foods with something containing vitamin C helps your body absorb more of it.
Weight Gain at This Stage
By the midpoint of pregnancy, most women have gained a noticeable amount of weight, though the “right” amount depends on your starting size. The general pattern is slower gain in the first trimester followed by a steadier pace of about half a pound to one pound per week through the second and third trimesters. For women who started pregnancy at a higher weight, guidelines suggest a total gain of 11 to 20 pounds across the entire pregnancy, at roughly half a pound per week during the second and third trimesters. Your provider can give you a more personalized target based on your pre-pregnancy BMI.