What pregnancy week 16 means
First flutters possible. “16 weeks pregnant” means 16 weeks have passed since the first day of the last menstrual period — the standard way pregnancy is dated. Conception usually happened about two weeks after that date, so the baby’s own age (fetal age) is roughly 14 weeks. Week 16 runs from 16 weeks 0 days to 16 weeks 6 days; on the following day the pregnancy is 17 weeks.
Your baby at 16 weeks
Muscles in the back and neck are getting stronger, so the baby holds the head more upright. The heart is now pumping a large volume of blood every day.
A common way to picture it: the baby is now about the size of an avocado — roughly about 11.6 cm and about 100 g. These are averages; babies grow at different rates, and ultrasound measurements vary.
Your body at 16 weeks
Some people — especially those who have been pregnant before — feel the first light movements, known as quickening, from around 16 weeks. It is often described as bubbles or flutters. In a first pregnancy it is commonly felt later, up to about 20–22 weeks.
Care and appointments around week 16
Mention any persistent headaches, swelling or changes in vision at your appointments; your provider will check your blood pressure regularly.
The timing of tests and appointments differs between countries and care providers. If anything worries you — such as bleeding, severe pain, fluid leaking, fever — contact your midwife, doctor or maternity unit straight away rather than waiting for your next appointment.
Week 16 in your pregnancy timeline
Week 16 is in the second trimester (weeks 14–27) and in pregnancy month 4, which covers roughly weeks 14–17. The third trimester begins in 12 weeks.
| Pregnancy start (first day of last period) | |
|---|---|
| Estimated conception | |
| Third trimester begins (28 weeks) | |
| Full term (39 weeks) | |
| Estimated due date (40 weeks) |
Dates assume you are exactly 16 weeks 0 days today. For dates based on your own last period, use the calculator above or the main Pregnancy Calculator.
16 weeks pregnant in days and months
16 weeks is 112 days of pregnancy — 40% of a 40-week pregnancy. Counted in calendar months, 16 weeks is about 3.7 months, which is usually described as month 4 of pregnancy. Months are only a rough grouping; healthcare professionals almost always talk in weeks and days because they are more precise. See Pregnancy Month Calculator for how weeks map to months.