The short answer
15 weeks = 4 months
At 15 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.
Hearing is starting to develop, and although the eyelids are still fused shut, the fetus can sense bright light from outside.
About the size of an apple
size comparison
10.1 cm
crown to rump (4.0 in)
70 g
average weight (2.5 oz)
The skin is thin and translucent, with blood vessels clearly visible beneath it. Taste buds are forming, and the bones of the inner ear are hardening. The legs have grown longer than the arms, and the fetus practices sucking, swallowing and even breathing motions with amniotic fluid.
Sizes and weights are averages — healthy babies vary widely, and your scan measurements are what count.
A gentle bump often becomes visible around now, especially in a second or later pregnancy. Some people notice a darker line down the belly (linea nigra) or patches of darker skin on the face. Sleep can start to feel less restful as the belly gets in the way, and vivid dreams are common.
Common symptoms this week
175
days to go
25
weeks to go
105
days so far
At 15 weeks 0 days you are 105 days into a 280-day pregnancy, which leaves 175 days — 25 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: 35 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 15 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 — 15+3 or 15w3d, 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 |
|---|---|---|---|
| 15 weeks 0 days (this page) | 15+0 | 105 | 175 |
| 15 weeks 1 day | 15+1 | 106 | 174 |
| 15 weeks 2 days | 15+2 | 107 | 173 |
| 15 weeks 3 days | 15+3 | 108 | 172 |
| 15 weeks 4 days | 15+4 | 109 | 171 |
| 15 weeks 5 days | 15+5 | 110 | 170 |
| 15 weeks 6 days | 15+6 | 111 | 169 |
At 15 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.
15 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 25 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 15 weeks 0 days you are 105 days into a 280-day pregnancy, so there are 175 days left until the 40-week mark — that's 25 weeks. The count drops by one for each day you move through week 15.
15 weeks is 105 days, counted from the first day of your last menstrual period (15 × 7 = 105). Add the days into your current week for the exact figure — for example 15 weeks 3 days is 108 days.