20 weeks pregnant: halfway, the 20-week scan and pre-eclampsia

At 20 weeks pregnant you're halfway there. Your baby weighs about 300g and is about 16cm long, KKH says, and has started keeping a newborn's hours: about 18 hours asleep and 6 awake. Your 20-week anomaly scan falls around now, and from this week KKH wants you to know the warning signs of pre-eclampsia.

Your baby at 20 weeks

Your baby's kicks may start to follow the sleep pattern, stronger when awake and quieter when asleep. KKH's planner says the eyelids stay sealed until about week 20, and the nostrils stay plugged until about the same time.

The 20-week scan

KKH runs this fetal anomaly scan between weeks 18 and 21 and uses it to look at your baby from head to toe for structural problems, and to screen for a low-lying placenta. NUH does its detailed scan at 20 weeks. No scan is 100% accurate, so some problems can be missed. Our 18 weeks pregnant guide covers what can limit the scan and finding out the sex.

Pre-eclampsia: the signs to act on

Pre-eclampsia develops from week 20 onwards, KKH explains. It usually shows up as high blood pressure, above 140/90mmHg, with protein in your urine, which is why both are checked at every visit. Left uncontrolled, it can cause seizures and damage other organs, and it can reduce blood flow through the placenta to your baby.

KKH asks you to seek help at once for any combination of these:

• a severe headache
• blurred vision or other changes in your sight
• severe nausea and vomiting
• pain in the upper right side of your tummy
• sudden swelling of your ankles or feet
• sudden puffiness of your face

Our guide to pre-eclampsia in Singapore covers who is at higher risk and how it's treated.

What's due in Singapore at 20 weeks

Daytime sleepiness is common now. KKH suggests a short lunchtime nap, and yoga, deep breathing, a massage or a warm bath before bed for better nights. For comparing hospitals before you book a delivery, see hospital maternity packages and the delivery cost calculator.

When to call the hospital

Any of the pre-eclampsia signs above, bleeding, fluid leaking, painful tightening, chest pain or breathlessness need help the same day, and the pre-eclampsia signs need it at once.

Where to go: KKH runs a 24-hour walk-in Urgent O&G Centre (Basement 1, Women's Tower) for pain and bleeding in pregnancies under 22 weeks. Milder bleeding or pain before 16 weeks can be booked into its Early Pregnancy Assessment Unit for the same or next working day. Other hospitals have their own O&G urgent services, so ask yours where to go.

Frequently asked questions

How big is a baby at 20 weeks pregnant?

About 16cm long and about 300g, KKH says.

What blood pressure counts as high in pregnancy?

KKH describes pre-eclampsia as blood pressure above 140/90mmHg with protein in the urine, developing from week 20.

Is 20 weeks halfway through pregnancy?

Yes. Pregnancy is counted as 40 weeks from the first day of your last period, so week 20 is the halfway mark.

20 weeks pregnant is how many months?

About four and a half months, counted from the first day of your last period.

Week by week. Previous week: 19 weeks pregnant. Next week: 21 weeks pregnant. Every week from 4 to 40: pregnancy week by week.