MHMW

Second trimester

25 weeks pregnant: what is happening this week

Week 25 of 42worked example

34.6 cm

Measured
head to heelabout the size of a courgette
This week runs
Thu, Jun 18, 2026 to Wed, Jun 24, 2026
Days to the estimated due date
112
Term window (37-42 weeks)
Thu, Sep 17, 2026 to Thu, Oct 22, 2026

The NHS publishes this figure for week 25, about the size of a courgette. It is an average from patient guidance rather than a measurement of any particular pregnancy, and the measurement basis changes at week 20 - see the note below the dates.

34.6 cm, courgette-length, and urine is being passed into the amniotic fluid, which cushions and keeps the temperature steady and is refreshed continuously. A loud noise nearby produces a jump and a kick. Hiccups happen, and they feel from the outside exactly like hiccups - a rhythmic tap every few seconds that has nothing to do with movement patterns and worries first-time parents unnecessarily. In a first pregnancy there is an antenatal appointment this week: bump measurement, a conversation about movements, a mental health check, and the beginning of the birth preferences discussion. Two practical deadlines land around here as well. Week 25 is the statutory deadline in the UK for telling an employer, and swelling in the hands, feet and face becomes common enough that the NHS spells out which combination of symptoms - a severe headache, vision problems, pain below the ribs - warrants an immediate call rather than a mention at the next appointment. Knowing that list is not the same as expecting to need it, and it is a lot easier to read now than to look up while feeling unwell.

Put your own dates on week 25

Week 1 began
Thu, Jan 1, 2026
Week 25 begins
Thu, Jun 18, 2026
Week 25 ends
Wed, Jun 24, 2026
Estimated due date
Thu, Oct 8, 2026

Dates run on ACOG's 280-day convention, the same arithmetic as the due date calculator. Share this week with your dates: /pregnancy/week-25?s=d:2026-10-08

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What the NHS describes this week

  • The NHS puts the foetus at around 34.6 cm from head to heel this week.
  • Urine is now passed into the amniotic fluid, which cushions and regulates temperature.
  • Loud noises produce jumping and kicking, and hiccups occur.

What happens around now

A 25-week antenatal appointment is scheduled in a first pregnancy. Week 25 is also the statutory UK deadline for notifying an employer. The NHS lists severe headache, vision problems and pain below the ribs as symptoms to report immediately rather than at the next appointment.

  • 25-week antenatal appointment in a first pregnancy - bump measurement, movements, mental health, birth preferences (NHS)

On the measurement. The NHS publishes a length for each week from 4 to 40. Up to week 19 it is measured head to bottom (crown to rump, the measurement a scan takes while the legs are curled). From week 20 it is measured head to heel, which is why the figure jumps from 15.3 cm at week 19 to 25.6 cm at week 20 - the baby did not grow 10 cm in a week, the ruler changed. The NHS states the change on its week 20 page.

Where week 25 comes from

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