Welcome to the 5th month of pregnancy! Over the past weeks, your body has already achieved incredible things, and your baby has reached important developmental milestones. Now is a wonderful time to enjoy your pregnancy more consciously and take good care of both yourself and your growing baby. Here’s what matters most in the 17th week of pregnancy.

How big is your baby in week 17 of pregnancy?

In the 17th week of pregnancy, your baby measures around 12 centimeters from head to bottom—roughly the size of an orange.

Week 17 of pregnancy: What’s changing for you

During pregnancy, your blood volume increases significantly. This puts more pressure on your veins, while the hormone progesterone makes their walls more elastic and permeable. As a result, visible vein changes such as spider veins, varicose veins, or hemorrhoids may develop.

Varicose veins and hemorrhoids can be uncomfortable or even painful, but there are ways to reduce the risk. A high-fiber diet, regular gentle exercise, and sufficient fluid intake can help keep digestion moving smoothly. Try to avoid standing for long periods or sitting with your legs crossed. Compression stockings can relieve pressure on your legs, and regularly elevating your feet may also bring relief. If you want to learn more about preventing hemorrhoids during pregnancy, you can find additional guidance in our dedicated article on the topic.

Week 17 of pregnancy: Your baby’s development

This week marks a very special milestone: your baby’s heartbeat has grown strong enough that it may now be audible through a stethoscope. While the heart has been beating since around the 5th week of pregnancy and visible on ultrasound shortly after, this is often the first time parents can hear it directly. 

In week 17, your baby’s body begins producing myelin. This protective layer surrounds nerve cells and the spinal cord and will later help transmit signals efficiently throughout the nervous system. At the same time, your baby’s bones continue to harden, gradually replacing cartilage. However, they will remain flexible for quite some time—an important feature for birth and early childhood.

The reproductive organs continue to develop: in girls, the uterus and vagina form further, while in boys, the penis and prostate continue to grow. From this week on, your baby also starts building small fat reserves. These help regulate body temperature and serve as an important energy source in the first days after birth, before breastfeeding is fully established.

By the 17th week of pregnancy, your baby’s facial features are becoming more defined. The eyes and ears are now almost in their final positions. Hearing continues to improve, and loud noises may already startle your baby. Sensitivity to touch is also increasing. If you and your partner haven’t started talking or singing to your baby yet, now is a great time to begin.

The umbilical cord

The umbilical cord is the vital connection between you and your baby via the placenta—and it’s a fascinating structure. Over the course of pregnancy, it grows to around 50 to 60 centimeters in length and about 2 centimeters in diameter to reliably supply your baby with nutrients and oxygen.

Its spiral shape allows it to stretch and contract easily, ensuring freedom of movement for your baby without compromising blood flow. A firm outer layer and a jelly-like protective substance help prevent kinks or compression. Inside the umbilical cord are three blood vessels: one vein transports oxygen- and nutrient-rich blood to your baby, while two arteries carry blood back to the placenta.

Your blood and your baby’s blood never mix directly. This separation is maintained by the placental barrier, which allows nutrients and maternal antibodies to pass through while blocking most bacteria and viruses.

What’s important right now

Avoid standing for long periods whenever possible. As your uterus grows, it can put pressure on the sciatic nerve, which may lead to lower back or leg pain.

Because of increased blood volume, you may notice that you sweat more easily. This can lead to a higher loss of important minerals such as iodine, calcium, magnesium, and iron. A balanced, nutrient-rich diet is especially important now to support your baby’s development. Your iron levels are checked regularly during prenatal appointments, and you can discuss with your healthcare provider whether supplements might be helpful for you.

Have you and your partner already started thinking about baby names? You still have time before making a final decision, but looking for a name together can be a lovely way to build anticipation. Our article “10 questions to ask yourself when choosing a name” offers helpful guidance. You can also explore the baby name feature in the LILLYDOO app, where you’ll find over 12,000 name ideas and can easily share favorites with your partner.

LILLYDOO tip

You may notice more freckles, dark spots, or other pigmentation changes during pregnancy. This is due to increased melanin production, which affects skin coloration. Darker nipples or a dark line running from the navel downward—the so-called linea nigra—are also common.

These pigmentation changes usually fade after birth or by the end of breastfeeding. However, your skin is more sensitive to sunlight during pregnancy, so be sure to use adequate sun protection and seek shade whenever possible.