Pregnancy Calculator — Week 31: Baby Size, Symptoms & Due Date
You are in week 31 of a standard singleton pregnancy. Below is a complete evidence-based snapshot — baby's growth, your body, nutrition, exercise, red flags and a doctor visit checklist for this exact week.
Pregnancy Calculator
Enter the first day of your last menstrual period (LMP). EDD = LMP + 280 days.
Baby at week 31
This week: All five senses functional. Fetus urinates ~500 ml/day into amniotic fluid.
Mother's body — what changes
In week 31 you may notice: Fundus 11 cm above navel. Heartburn worsens. Difficulty sleeping.
Nutrition & supplements
Add ~450 kcal/day. Increase iron and DHA — brain growth peaks now. Split meals into 5–6 small portions to control heartburn and stable glucose.
Safe exercise
Reduce intensity but keep moving. Pelvic floor + squats prepare for labour. Avoid contact sports, ski, horse-riding and hot yoga.
Doctor visit checklist — week 31
- ✓Attend antenatal / breastfeeding classes
- ✓Blood pressure + weight + urine dipstick at every visit
- ✓Fetal heart tones from week 10–12 (Doppler)
Warning signs — call your provider immediately
- ⚠Heavy bleeding (soaking a pad in an hour)
- ⚠Severe abdominal pain that does not ease
- ⚠Fever above 38°C / 100.4°F
- ⚠Regular contractions before 37 weeks (preterm labour)
- ⚠Reduced fetal movement — fewer than 10 kicks in 2 hours
- ⚠Sudden swelling of face/hands + severe headache (preeclampsia)
- ⚠Bright red bleeding (placental abruption or previa)
Week 31 — Frequently asked questions
How accurate is the Pregnancy Calculator at week 31?
The calculator uses standard gestational-age arithmetic (LMP + 280 days for standard; egg retrieval + 266 days for IVF day-5). Ultrasound crown-rump length between weeks 8–13 is more accurate (±5 days) than LMP — adjust EDD accordingly if the scan differs by more than 7 days.
What size is my baby at week 31?
Approximately the size of a coconut — length 41.1 cm and weight 1500 g. These are median values from ACOG, NHS UK and Mayo Clinic references.
Which symptoms are normal in week 31?
Fundus 11 cm above navel. Heartburn worsens. Difficulty sleeping. Every pregnancy is different — call your provider if anything on the warning-signs list appears.
Should I have an ultrasound at week 31?
Attend antenatal / breastfeeding classes. Routine scan windows are: dating (10–13w), anatomy (18–22w), growth (28–32w).
How much weight should I gain by week 31?
Approximately 10.0 kg cumulative if you started at a normal BMI (IOM guideline). Underweight mothers gain more; overweight mothers less.
What is my EDD if today is week 31?
Your estimated due date is 9 weeks from today. Calculator adds (280 − 7 × 31) days to today's date.
Can I travel during week 31?
Most airlines restrict flying after week 36 (32 for twins). Carry your antenatal notes and check-in seat with legroom.
Content aligned with ACOG, NHS UK and Mayo Clinic. Reviewed by Dr. Maria Rehman, MD (OB/GYN). This page is educational and does not replace personal medical advice — call your obstetrician for any concern.