The short answer
20 weeks = 5 months
At 20 weeks pregnant, you are about 5 months pregnant — in month 5 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.
Halfway there! The detailed anatomy scan usually happens around now, and it’s often possible to learn the baby’s sex if you want to.
About the size of a banana
size comparison
25.6 cm
crown to heel (10.1 in)
300 g
average weight (10.6 oz)
From this week measurements switch from crown-rump to crown-heel, so length figures jump. The fetus is swallowing more amniotic fluid, which is good practice for the digestive system, and is producing meconium — the dark, sticky first bowel movement. The skin is thickening into layers, and permanent tooth buds are forming behind the baby teeth.
Sizes and weights are averages — healthy babies vary widely, and your scan measurements are what count.
The top of the uterus reaches your navel around now, and your provider will start measuring fundal height at each visit. Your belly button may flatten or pop outward. Heartburn, snoring and shortness of breath on stairs are common as organs are gently pushed upward.
Common symptoms this week
140
days to go
20
weeks to go
140
days so far
At 20 weeks 0 days you are 140 days into a 280-day pregnancy, which leaves 140 days — 20 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: 56 days until the third trimester (28 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 20 falls in month 5, 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 — 20+3 or 20w3d, 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 |
|---|---|---|---|
| 20 weeks 0 days (this page) | 20+0 | 140 | 140 |
| 20 weeks 1 day | 20+1 | 141 | 139 |
| 20 weeks 2 days | 20+2 | 142 | 138 |
| 20 weeks 3 days | 20+3 | 143 | 137 |
| 20 weeks 4 days | 20+4 | 144 | 136 |
| 20 weeks 5 days | 20+5 | 145 | 135 |
| 20 weeks 6 days | 20+6 | 146 | 134 |
At 20 weeks pregnant, you are about 5 months pregnant — in month 5 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.
20 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 20 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 20 weeks 0 days you are 140 days into a 280-day pregnancy, so there are 140 days left until the 40-week mark — that's 20 weeks. The count drops by one for each day you move through week 20.
20 weeks is 140 days, counted from the first day of your last menstrual period (20 × 7 = 140). Add the days into your current week for the exact figure — for example 20 weeks 3 days is 143 days.