Also written 15+4 or 15w4d
The short answer
15 weeks 4 days = 4 months
At 15 weeks 4 days pregnant you are about 4 months pregnant — day 109 of your pregnancy, in month 4 and your second trimester.
Not sure of your exact week and day? The pregnancy week calculator works it out from your last period, due date or conception date.
171
days to go
24
whole weeks + 3d
39%
complete
You are 109 days into a 280-day pregnancy, so there are 171 days — 24 weeks and 3 days — left until you reach 40 weeks. Bear in mind that 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: 31 days until the halfway point (20 weeks 0 days).
Months of pregnancy are counted in uneven buckets of 4 to 5 weeks, arranged so that the full 40 weeks fits into 9 calendar months. Week 15 sits inside month 4, and it stays there for all seven days of the week — so 15 weeks 0 days and 15 weeks 4 days are both "4 months pregnant".
If you want the strict calendar answer instead, divide by the real length of a month rather than by four: 109 days ÷ 30.4375 days per month = 3.6 calendar months. That figure drifts from the bucket-based month number, which is exactly why your care team sticks to weeks and days.
The days part matters clinically even when the month doesn't. Screening windows, term definitions and induction timing are all set by exact week and day — full term starts at 39 weeks 0 days, not "9 months". See the full weeks to months chart for every week.
Hearing is starting to develop, and although the eyelids are still fused shut, the fetus can sense bright light from outside.
Read the full week 15 breakdown →
| Week + day | Months pregnant | Days pregnant | Days to go |
|---|---|---|---|
| 15 weeks | about 4 months | 105 | 175 |
| 15 weeks 1 day | about 4 months | 106 | 174 |
| 15 weeks 2 days | about 4 months | 107 | 173 |
| 15 weeks 3 days | about 4 months | 108 | 172 |
| 15 weeks 4 days (you) | about 4 months | 109 | 171 |
| 15 weeks 5 days | about 4 months | 110 | 170 |
| 15 weeks 6 days | about 4 months | 111 | 169 |
At 15 weeks 4 days pregnant you are about 4 months pregnant — day 109 of your pregnancy, in month 4 and your second trimester. Months of pregnancy are counted as uneven 4–5 week buckets so the full 40 weeks fits into 9 calendar months, which is why the extra 4 days doesn't change your month number.
"15+4" is the shorthand your midwife or doctor uses for 15 weeks 4 days — the number before the plus is completed weeks, the number after it is completed days into the current week. You may also see it written 15w4d. Both mean exactly the same thing.
15 weeks 4 days is 109 days, counted from the first day of your last menstrual period (15 × 7 = 105, plus 4). That leaves 171 days — 24 weeks and 3 days — until the 40-week mark.
About 24 weeks and 3 days until 40 weeks. Only about 1 in 20 babies arrives exactly on the estimated due date, though — most are born within two weeks on either side of it.
15 weeks 4 days 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.