20 weeks pregnant: symptoms and baby development
Halfway. Kicking, turning, practicing.
Second trimesterMonth 55 min read
By Solesia, from public clinical guidanceUpdated
Halfway. Twenty weeks behind you and, give or take, twenty ahead, and for many people this is the week you lie in a dim room for the better part of an hour while someone traces every part of your baby on a screen: the chambers of the heart, the curve of the spine, the fingers, and, if you want to know, the sex. They are kicking, turning and sucking their thumb in there, and if you have not felt them yet, this is often when the flutters become impossible to miss. Heartburn and leg cramps at night are the new arrivals for you.
How big is your baby at 20 weeks
About the size of a banana
10 in long·11.2 oz
Baby development at 20 weeks
At 20 weeks your baby measures about 10.0 inches from head to heel and weighs around 11.2 ounces, roughly a banana. The jump in length from last week is the tape measure, not a growth spurt: until 19 weeks babies are measured crown to rump because the legs are folded up; from 20 they are measured with the legs included.
They are covered in vernix, the white greasy coating that keeps the skin from soaking in the fluid, and under it the skin is getting thicker and dividing into its layers. They are practicing everything: kicking, punching, turning, and sucking a thumb, which is rehearsal for feeding. They swallow fluid and pass small amounts of urine, and the first stool, a dark sticky substance called meconium, is beginning to collect in the gut.
Ultrasound this week can see all of it. The heart, with four chambers and valves opening and closing about 150 times a minute; the spine in one long line; kidneys with a bladder that fills and empties; the fingers, counted; the bones of the face.
Your body at 20 weeks
The top of your uterus is level with your belly button now, and your provider will start measuring the distance from the pubic bone to the top of it at each visit: the fundal height, in centimeters, which tracks the number of weeks. Heartburn is expected from about now, as the uterus pushes the stomach up and pregnancy hormones relax the valve that keeps acid down. Smaller meals, an upright hour after eating and a raised pillow at night take the edge off; an antacid is fine if you need one.
Leg cramps at night are common from the second half of pregnancy. The calf muscle seizes, usually just as you are drifting off or in the small hours. Stretch the leg out and pull the toes toward the shin, and it releases in seconds; walking it off finishes the job. Stretching the calves before bed and staying hydrated make them rarer.
Movements are becoming clearer and, if you have been waiting, this is often the week. They may feel like gentle taps now rather than bubbles, and they come and go through the day. There is nothing to count for weeks yet. What you are doing now is learning what your baby feels like, and when in the day they tend to be busy.
Common pregnancy symptoms at 20 weeks
- Heartburn. The stomach is squeezed and its valve relaxed. Small meals, upright after eating, pillow raised at night.
- Leg cramps at night. A calf that seizes. Straighten the leg and pull your toes toward you; stretch calves before bed.
- Round ligament pain. Sudden moves pull on the cords holding the uterus. Turn and rise slowly.
- Backache. A heavier front and looser joints. Flat shoes, and a pillow between your knees.
- Stretch marks. Skin stretching faster than it adapts. Moisturize for comfort; they fade after birth.
- Feeling hot. Extra blood near the skin. Light layers, cool rooms, and water close by.
- Nosebleeds. A swollen nose lining. Pinch the soft part for ten minutes; a humidifier at night.
When to call your provider at 20 weeks
From now on, a headache that will not shift, changes in your vision, or sudden swelling of your face and hands are worth a same-day call. Almost always it is nothing; it is quick to check.
Two things are worth a same-day call at any point in pregnancy: bleeding that is more than spotting, and pain that is severe or does not ease. From the second trimester, add fluid leaking and any change in your baby’s usual pattern of movement. You do not need to be sure something is wrong to call; that is what the number is for.
What to do at 20 weeks
- Anatomy ultrasound. The detailed scan is often booked right at 20 weeks. It checks every organ and limb, measures growth, and looks at the placenta and the fluid. Ask whether they can write the sex down instead of saying it, if you want a choice.
- Prenatal visit. With visits every four weeks, one often lands now: blood pressure, urine, weight, the heartbeat, and from this week a fundal height measurement.
- Whooping cough vaccine, ahead. The Tdap shot is given between 27 and 36 weeks in the US. Nothing to do yet, but it belongs on the list for the next trimester.
- Childbirth class. Halfway is when many people sign up. Classes at 24 to 32 weeks leave time to practice what they teach.
Common questions at 20 weeks
How many months is 20 weeks pregnant?
About four and a half months, and the halfway point of a 40-week pregnancy. Week 20 sits in the fifth month by the usual count and in the second trimester, which runs to the end of week 27. Twenty weeks to go, more or less; babies arrive anywhere from 37 to 42 weeks.
Why did my baby’s length jump this week?
Because of how they are measured. Up to 19 weeks the length runs from the top of the head to the bottom, with the legs left out because they are folded. From 20 weeks it runs head to heel, and the legs add several inches at once. Your baby grew about an inch; the tape measure did the rest.
What can the 20-week ultrasound show?
The heart and its four chambers, the brain, spine, kidneys, bladder, stomach, arms, legs, hands and feet, the face and lips, the placenta and the amount of fluid. It measures the head, belly and thigh bone to estimate size. It can usually tell the sex. About one scan in fifty finds something that needs a second look, and many of those turn out to be nothing.
Can my baby hear me at 20 weeks?
Yes, the sounds inside you and, increasingly, the louder ones outside. Your voice reaches them best, because it travels through your body as well as the air. A loud bang can make them startle. Talking and singing are worth doing; newborns recognize and settle to the voices they heard before birth.
Written from public clinical guidance, including NHS: Week 20, ACOG: How your baby grows, ACOG: Changes in your body, NHS: Indigestion and heartburn, NHS: Your baby’s movements and ACOG: The Tdap vaccine and pregnancy. This page is general information, not medical advice, and does not replace your provider.