The short answer
13 weeks = 3 months
At 13 weeks pregnant, you are about 3 months pregnant — in month 3 of your pregnancy and in your first trimester.
Not sure of your week? Use the pregnancy week calculator to find it from your last period, due date or conception date.
Vocal cords are forming and the first trimester is wrapping up. The fetus is roughly the size of a lemon.
About the size of a pea pod
size comparison
7.4 cm
crown to rump (2.9 in)
23 g
average weight (0.8 oz)
The body is now catching up with the head, which drops from about half to about a third of total length. Fingerprints are forming as ridges on the fingertips, and the intestines are starting to practice the muscle contractions they will use to digest food. The placenta is fully developed and takes over hormone production from the ovaries.
Sizes and weights are averages — healthy babies vary widely, and your scan measurements are what count.
Many people describe a turning point around now: nausea fading, tiredness lifting and appetite back. Breasts may begin producing colostrum, the thick early milk, though you may not notice. A visible bump is still a few weeks off for most first pregnancies, but clothes may already sit differently.
Common symptoms this week
189
days to go
27
weeks to go
91
days so far
At 13 weeks 0 days you are 91 days into a 280-day pregnancy, which leaves 189 days — 27 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: 7 days until the second trimester (14 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 13 falls in month 3, in the first 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 — 13+3 or 13w3d, 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 |
|---|---|---|---|
| 13 weeks 0 days (this page) | 13+0 | 91 | 189 |
| 13 weeks 1 day | 13+1 | 92 | 188 |
| 13 weeks 2 days | 13+2 | 93 | 187 |
| 13 weeks 3 days | 13+3 | 94 | 186 |
| 13 weeks 4 days | 13+4 | 95 | 185 |
| 13 weeks 5 days | 13+5 | 96 | 184 |
| 13 weeks 6 days | 13+6 | 97 | 183 |
At 13 weeks pregnant, you are about 3 months pregnant — in month 3 of your pregnancy and in your first trimester. Months of pregnancy are counted as uneven 4–5 week buckets so that the full 40 weeks fits into 9 calendar months.
13 weeks is in the first trimester, which runs from week 0 through 13 weeks 6 days. The second trimester begins at 14 weeks 0 days.
About 27 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 13 weeks 0 days you are 91 days into a 280-day pregnancy, so there are 189 days left until the 40-week mark — that's 27 weeks. The count drops by one for each day you move through week 13.
13 weeks is 91 days, counted from the first day of your last menstrual period (13 × 7 = 91). Add the days into your current week for the exact figure — for example 13 weeks 3 days is 94 days.