16 weeks pregnant means 16+0 to 16+6 weeks from the first day of your last period: about 3 months and 21 days, so you are in the 4th month. From this week some mothers start to feel the first movements, and the baby's heartbeat can be heard with a handheld Doppler.
16 weeks pregnant (16+0 to 16+6 weeks) is about 3 months and 21 days from the first day of your last period. You are in the 4th month.
The NHS says your baby is now around 11.6 cm from head to bottom, the size of an avocado. Your baby is starting to pull faces, but any smiling or frowning is random because there is no muscle control yet. The developing nervous system lets the baby move arms and legs, form fists and punch around inside you. The NHS says you might feel kicks from week 17 onwards.
ACOG's summary for weeks 13 to 16 says that by the end of this stage the long bones have hardened, the legs have developed, hearing has started to develop and the lungs have begun forming the tissue that will exchange oxygen after birth.
Your baby is growing fast, and you may have put on some weight in recent weeks too. At 16 weeks the top of the womb is about halfway between the pubic bone and the belly button (UpToDate, 2026), so your bump becomes more noticeable.
Constipation is common in pregnancy. The NHS suggests high-fibre foods (wholemeal bread, fruit and vegetables, beans and lentils), regular exercise and plenty of water; iron tablets can make it worse, but do not stop any medicine without talking to your doctor. For most people nausea is expected to settle by 16 to 20 weeks (NICE; UpToDate).
If you have gas heating or a stove at home, check that your carbon monoxide detector works: the NHS reminds you that this gas cannot be seen or smelled and can come from cigarette smoke or faulty or poorly ventilated heating and cooking appliances.
Turkish Ministry of Health guideline (2026): the baby's heartbeat can be heard with a handheld Doppler from 16 weeks, at a rate of 110 to 160 beats per minute; the guideline lists not hearing the heartbeat by handheld Doppler after 16 weeks as a reason for specialist review. Iron supplements start from 16 weeks for women without anaemia. If combined screening was not done, the triple/quad test and AFP are done at 16 to 20 weeks. The next routine visit is between 18 and 24 weeks. The NHS advises against using a home Doppler: hearing a heartbeat does not mean your baby is well.
NICE NG201 recommends a 16-week (14 to 18 weeks) appointment with a blood pressure check, a urine test for protein and a discussion of your booking blood test results (including HIV, hepatitis B and syphilis, according to the NHS). Protein in the urine matters because of pre-eclampsia.
Timing of the whooping cough (Tdap) vaccine differs: the NHS offers it from 16 to 32 weeks (usually around 20 weeks), the Turkish Ministry of Health at 18 to 24 weeks (or until the end of week 32 if missed), and the US advice reported by UpToDate ideally at 27 to 36 weeks.
| Symptom | Usually | Seek care if |
|---|---|---|
| Constipation and bloating | Common in pregnancy; fibre, activity and fluids help (NHS). | If you have severe tummy pain, vomiting or bleeding from the back passage. |
| Nausea that has not gone | It settles by 16 to 20 weeks for most people but lasts longer for some (UpToDate). | If you cannot keep anything down (severe nausea and vomiting is a danger sign in the Turkish Ministry of Health guideline). |
| Not feeling movements yet | In a first pregnancy, movements may not be felt until after 20 weeks (NHS). | Tell your midwife or doctor if you have felt nothing by 24 weeks (NHS); the Turkish Ministry of Health guideline treats no movements after 20 weeks as a reason for referral. |
These are danger signs or emergency referral criteria in the Turkish Ministry of Health guideline; contact your doctor or go to the nearest emergency department without waiting. NICE recommends a hospital review for any unexplained bleeding after 13 weeks, and anti-D for women who are RhD negative and at risk of isoimmunisation. The NHS says to call immediately if your baby's movements change, without waiting until the next day, even in the middle of the night.
Days 112 to 118 from the first day of your last period, or about 3 months and 21 days. You are in the 4th month.
The NHS page on baby movements says between 16 and 24 weeks; in a first pregnancy it is normal not to feel them until after 20 weeks. UpToDate says mothers usually notice movements at 16 to 20 weeks, earlier if they have given birth before. First movements may feel like flutters or bubbles.
Usually not reliably on ultrasound yet; UpToDate notes that ultrasound generally shows the sex at 17 to 20 weeks. A cell-free DNA test (NIPT) can report the sex along with chromosome screening; a wrong result is possible.
According to the WHO fetal growth charts (2017), the median (50th percentile) estimated fetal weight at 16 weeks is 144 g, and the 10th to 90th percentile range is 124 to 166 g. These are reference values from ultrasound measurements in low-risk pregnancies in ten countries; the authors note differences between countries, with maternal factors and with fetal sex, and say the charts may need adjusting for local use. UpToDate adds that ultrasound weight estimates are generally not useful before about 24 weeks. The NHS gives a length of about 11.6 cm from head to bottom.
It varies from person to person. On examination, the top of the womb is felt about halfway between the pubic bone and the belly button at 16 weeks (UpToDate, 2026).
Last updated: . All sources have been confirmed with their latest versions. This content is for educational purposes and is not a substitute for a doctor's examination.