The short answer
16 weeks = 4 months
At 16 weeks pregnant, you are about 4 months pregnant — in month 4 of your pregnancy and in your second trimester.
Not sure of your week? Use the pregnancy week calculator to find it from your last period, due date or conception date.
Limb movements are becoming coordinated — some people feel the first flutters between now and about 25 weeks, especially in second pregnancies.
About the size of an avocado
size comparison
11.6 cm
crown to rump (4.6 in)
100 g
average weight (3.5 oz)
The eyes are now facing forward rather than to the sides, and they can move slowly behind closed lids. The heart pumps around 25 liters of blood a day, and the circulatory and urinary systems are fully functional. Toenails are appearing, and the ears can pick up faint sounds from inside your body.
Sizes and weights are averages — healthy babies vary widely, and your scan measurements are what count.
Your uterus is roughly halfway between the pubic bone and the navel, and its weight can begin to shift your center of gravity. Lower back ache may start as posture adjusts. Many people describe glowing skin and thicker hair around now, thanks to higher blood flow and slower hair shedding.
Common symptoms this week
168
days to go
24
weeks to go
112
days so far
At 16 weeks 0 days you are 112 days into a 280-day pregnancy, which leaves 168 days — 24 weeks — until 40 weeks. That number drops by one for every day you move through this week. Remember the due date is an estimate: only about 1 in 20 babies is born on it, and most arrive within two weeks on either side.
Next milestone: 28 days until the halfway point (20 weeks 0 days).
A calendar month averages about 4.3 weeks — not 4 — so you can't just divide your week number by four. Instead, months of pregnancy are counted as uneven buckets of 4 to 5 weeks, arranged so the full 40 weeks fits into 9 calendar months. Week 16 falls in month 4, in the second trimester.
Your care team will always use weeks and days rather than months, because screening windows and term definitions are set by exact week — months are just the everyday shorthand. For the full conversion, see the weeks to months chart, or go the other way with the months-to-weeks guide.
Your notes will show a week and a day — 16+3 or 16w3d, for example. Pick the exact day you are on for its own day count, countdown and month answer.
| Week + day | Shorthand | Days pregnant | Days to go |
|---|---|---|---|
| 16 weeks 0 days (this page) | 16+0 | 112 | 168 |
| 16 weeks 1 day | 16+1 | 113 | 167 |
| 16 weeks 2 days | 16+2 | 114 | 166 |
| 16 weeks 3 days | 16+3 | 115 | 165 |
| 16 weeks 4 days | 16+4 | 116 | 164 |
| 16 weeks 5 days | 16+5 | 117 | 163 |
| 16 weeks 6 days | 16+6 | 118 | 162 |
At 16 weeks pregnant, you are about 4 months pregnant — in month 4 of your pregnancy and in your second trimester. Months of pregnancy are counted as uneven 4–5 week buckets so that the full 40 weeks fits into 9 calendar months.
16 weeks is in the second trimester, which runs from 14 weeks 0 days through 27 weeks 6 days. The third trimester begins at 28 weeks 0 days.
About 24 weeks until the 40-week mark — though only about 1 in 20 babies arrives exactly on the due date. Most are born within two weeks on either side of it.
At 16 weeks 0 days you are 112 days into a 280-day pregnancy, so there are 168 days left until the 40-week mark — that's 24 weeks. The count drops by one for each day you move through week 16.
16 weeks is 112 days, counted from the first day of your last menstrual period (16 × 7 = 112). Add the days into your current week for the exact figure — for example 16 weeks 3 days is 115 days.