At 25 weeks your baby is about 31.5 cm and 700 grams — roughly an aubergine — and is now genuinely learning the sound of your voice, alongside other familiar voices and sounds heard repeatedly.
The short answer: hearing is sharp enough now that familiar voices are being learned, not just detected — a real head start on the preference newborns show for their mother's voice. The nostrils are opening and making practice breathing movements, and capillaries filling with blood give the skin a healthier pink tone. For you, pelvic and pubic pain often start as the joint at the front of the pelvis loosens to prepare for birth, and heartburn tends to worsen.
Your baby this week
The nostrils, previously plugged, are opening, and practice breathing movements using the nose and chest have begun — no air moves yet, but the muscular pattern is being rehearsed. Capillaries just beneath the skin are filling with blood, giving a healthier pink colour than the more translucent, reddish look of earlier weeks.
Hearing has developed enough for genuine recognition rather than simple detection — your voice, your partner's voice, and music heard repeatedly are all being learned to some degree, which is part of why newborns show a documented preference for their mother's voice from the earliest hours after birth.
Your body this week
Your uterus is now roughly the size of a football. Pain at the front of the pelvis — where the two pubic bones meet at the symphysis pubis — is common from around now, driven by relaxin loosening the joint in preparation for birth. It tends to worsen with getting out of a car, climbing stairs, or turning over in bed. A pregnancy support belt and physiotherapy referral both genuinely help; it is not something to simply push through.
Heartburn often becomes more frequent, as the growing uterus pushes the stomach further upward on top of the valve-relaxing effect of progesterone. Our heartburn guide covers safe antacids and which eating habits help most.
Tests and appointments
Tests and scans around now: Still within the 24-28 week window for the glucose tolerance test.
Exact timing varies by country and by your own care plan — your doctor or midwife will confirm the schedule that applies to you.
Still within the glucose tolerance test window if it has not yet been done — the deadline is 28 weeks.
✅ Worth doing this week
- Talk, sing and play music — voices and sounds heard now are genuinely being learned
- Ask about a support belt if pelvic or pubic pain has started, rather than pushing through it
- Cut down on salty food, especially in the evening, to ease swelling overnight
- Try a pregnancy pillow under the belly and between the knees for better sleep support
- Book the glucose test now if the window is closing and it has not happened
When to call your doctor
Call the same day if: you have bleeding, severe or one-sided abdominal pain, a severe headache with visual disturbance or sudden swelling of the face and hands, fainting, a temperature above 38°C, or regular tightenings. Pelvic pain that is severe enough to prevent walking, rather than merely uncomfortable, is worth an earlier appointment rather than waiting.
FAQ — 25 weeks pregnant
Can the baby really recognise my voice by 25 weeks?
Yes — hearing has developed enough that familiar sounds heard repeatedly, especially your voice, are genuinely being learned. This is one reason newborns show a documented preference for their mother's voice within hours of birth. Your partner's voice and music you listen to regularly are picked up too, just less distinctly than sounds transmitted through your own body.
What is symphysis pubis pain?
Pain at the front of the pelvis, where the two pubic bones meet at a joint called the symphysis pubis. The hormone relaxin loosens this joint in preparation for birth, and in some women it loosens unevenly or too much, causing pain — worse with movements like getting out of a car, climbing stairs, or turning over in bed. It is common, manageable with physiotherapy and support belts, and not a sign anything is wrong with the baby.
How big is the baby at 25 weeks?
About 31.5 cm and 700 grams — roughly an aubergine. Capillaries under the skin are filling with blood, giving a healthier pink colour than the more translucent, reddish appearance of earlier weeks.
Why is heartburn getting worse at 25 weeks?
The uterus has grown large enough to push the stomach further upward, on top of progesterone already relaxing the valve that normally keeps stomach acid down. The combination tends to make heartburn more frequent and more noticeable through the second half of pregnancy. Smaller, more frequent meals and staying upright after eating both help.
Week 25 at a glance
At 25 weeks your baby is about 31.5 cm and 700 grams, with hearing sharp enough to genuinely learn familiar voices, open nostrils practising breathing movements, and a healthier pink skin tone as capillaries fill with blood. For you, pelvic and pubic pain often start as relaxin loosens the joint at the front of the pelvis in preparation for birth, and heartburn tends to worsen as the uterus pushes the stomach further up.
Inside Baby Novum: log pelvic pain and other symptoms as they develop, and the safe foods guide rates 240 items by trimester — useful when heartburn starts narrowing what feels comfortable to eat.