Your baby this week
Fine, soft hair called lanugo covers your baby's skin, and eyebrows and eyelashes are coming in. The eyes are still closed but can sense light, and hearing is starting to develop.
At 15 weeks your baby's skin is still thin and see-through, with blood vessels visible underneath. The bones keep hardening, so the skeleton shows up more clearly on ultrasound. Your baby moves, stretches and may turn away from bright light, even though the eyelids are still closed. Many parents start wondering about the baby's sex: it's often visible on ultrasound from mid-pregnancy, and more reliably at the anatomy scan around 18 to 22 weeks if the baby's position allows. For you, a stuffy nose and bleeding gums are common because of extra blood flow. A soft toothbrush and saline spray can help; ask a pharmacist before using decongestant sprays for more than a few days.
By the numbers
Week 15 covers days 105 to 111 counted from the first day of your last period, which is 38% of a 40-week pregnancy. About 175 days remain until a 40-week due date. Since last week, an average baby gains about 0.8 oz (24 g). By date of conception, your baby is about 13 weeks old.
Pregnancy is dated from the first day of your last period, so conception happens around week 2. Your due date is 280 days (40 weeks) from that day, and an early ultrasound may adjust it.
Your body
Stuffy noses, nosebleeds and bleeding gums are common because of increased blood flow. A soft toothbrush and a humidifier can help.
Tests and to-dos this week
The quad screen window is open from 15 to 22 weeks if you chose it. Regular, moderate exercise like walking or swimming is a good idea unless your provider says otherwise.
Quad screen (optional) · weeks 15–22 · test
Coming up: Anatomy ultrasound (from week 18). Full prenatal visit schedule
Tips for the second trimester
- Most healthy pregnant people are advised to get about 150 minutes of moderate activity a week, such as walking or swimming.
- Your recommended weight gain depends on your pre-pregnancy BMI, and gain usually speeds up in the second trimester.
- Once you feel your baby regularly, learn their usual pattern; a change in pattern matters more than any count.
- The flu shot is recommended at any point in pregnancy during flu season.
Call your provider or labor and delivery right away if you have:
- vaginal bleeding or leaking fluid
- regular contractions or pelvic pressure before 37 weeks
- a severe headache, vision changes, or sudden swelling of the face or hands
- a fever of 100.4 °F (38 °C) or higher, or painful urination
- after 24 weeks, your baby moving less or differently
In an emergency, call 911.
Last week and next week
Last week (14): Your baby's head is coming into better proportion with the body.
Next week (16): Your baby can now make fleeting facial expressions and curl the hands into fists.
Frequently asked questions
How big is the baby at 15 weeks?
About the size of an apple: about 3.9 in (10 cm) · 4 oz (114 g), measured crown to rump. These are rounded averages, and every baby grows at their own pace.
How many months is 15 weeks pregnant?
15 weeks is in month 4 and the second trimester. About 25 weeks (175 days) remain until a 40-week due date. Months are approximate; providers count weeks and days.
When can you find out the baby's sex?
Cell-free DNA screening can indicate it from about 10 weeks. On ultrasound, the anatomy scan at 18 to 22 weeks is most reliable, as long as the baby's position allows a clear view.
What's the next test or appointment after week 15?
Next up: Anatomy ultrasound, from week 18. Your provider may schedule things differently depending on your health and local practice.
Sources
- WHO Fetal Growth Charts (Kiserud et al., PLoS Med 2017)
- INTERGROWTH-21st crown-rump length standard (Papageorghiou et al., 2014)
- Hadlock et al.: In utero fetal weight standard (Radiology 1991)
- NHS: Week-by-week guide to pregnancy
- NHS: Pregnancy symptoms you need to get help for
- ACOG: How Your Fetus Grows During Pregnancy
- ACOG: Routine Tests During Pregnancy
- ACOG: Prenatal Genetic Screening Tests
- CDC: Vaccine Recommendations Before, During, and After Pregnancy
- Office on Women's Health: Prenatal care and tests
- Hungarian Decree 26/2014 (IV. 8.) EMMI on prenatal care
- NNGYK (Hungary): 2026 vaccination methodology letter
- ACOG – Group B Strep and Pregnancy (Committee Opinion 797)
- ACOG – The Rh Factor
Last reviewed: November 14, 2026 · Kitpebble editorial team
This page is for general information. It isn't medical advice or a diagnosis and doesn't replace your OB-GYN or midwife. Sizes are rounded averages. Our editorial policy