Pregnancy basics: seven numbers worth knowing
Seven numbers cover most early pregnancy questions: 280 days from your last period to your due date; no more than 200mg of caffeine a day; 150 minutes of moderate activity a week; first movements between 16 and 24 weeks; 10 to 12.5kg typical weight gain; hospital bag packed by 37 weeks; and call your midwife when contractions come every 5 minutes or more often.
Pregnancy advice comes at you from every direction. Most of it reduces to a few numbers, and each of these has a public-health source behind it.
280 days
A due date is 280 days, or 40 weeks, from the first day of your last period. The NHS describes a normal pregnancy as lasting anywhere from 37 to 42 weeks, so treat the date as the middle of a window. Work out yours.
200mg of caffeine
The NHS limit is 200mg a day. Caffeine hides in tea, cola, energy drinks and chocolate as well as coffee, so it adds up faster than you expect.
150 minutes of activity
The NHS recommends 150 minutes of moderate activity a week in pregnancy, including muscle strengthening. It does not need to happen in one go: walking, swimming and yoga all count.
16 to 24 weeks
This is when the NHS says you should start to feel your baby move. With a first baby it may be after 20 weeks. If you have felt nothing by 24 weeks, tell your midwife. Later on, a change in the usual pattern is a reason to call immediately, at any hour.
10 to 12.5kg
Most pregnant women gain between 10kg and 12.5kg (22lb to 28lb), mostly after week 20, according to the NHS. US guidelines give a range based on your BMI before pregnancy; see yours.
37 weeks
Have your hospital bag packed by now. The NHS suggests at least 3 weeks before the due date, and only about 1 in 20 babies arrive on the day. The hospital bag checklist has the full NHS list.
5 minutes
The NHS says to call your midwife or maternity unit when you are having regular contractions every 5 minutes or more often, or sooner if you are worried. A contraction timer does the arithmetic.
And one that is not a number
Read the label on your skincare. The short list of ingredients to avoid in pregnancy starts with retinoids.
Questions, answered
How much caffeine can I have when pregnant?
The NHS says you should not have more than 200mg of caffeine a day. Caffeine is in coffee, tea, cola, energy drinks and chocolate.
How much exercise should I do in pregnancy?
The NHS recommends aiming for 150 minutes of moderate intensity activity a week, including muscle strengthening exercises. Walking, swimming and yoga can all count.
When does a pregnancy reach full term?
ACOG defines full term as 39 weeks 0 days to 40 weeks 6 days. Early term is 37 weeks 0 days to 38 weeks 6 days.
Sources
- NHS: Due date calculator
- NHS: Foods to avoid in pregnancy
- NHS: Exercise in pregnancy
- NHS: Your baby's movements
- NHS: Weight gain in pregnancy
- NHS: Pack your bag for labour
- NHS: Signs that labour has begun
- ACOG Committee Opinion 579: Definition of Term Pregnancy
Sources last checked on 9 November 2026.
This guide is educational and does not replace advice from your midwife, health visitor or doctor. If you are worried about yourself or your baby, contact them, or your local emergency number in an emergency.