IVF Pregnancy Calculator — Week 13 (Day 3 & Day 5 Transfer)
You are 13 weeks pregnant after IVF (gestational age counted from egg retrieval + 14 days for day-5 transfer, +12 days for day-3 transfer). Below is what your embryologist and REI clinic expect at this exact stage.
IVF Pregnancy Calculator
Enter your egg retrieval date and select day-3 or day-5 transfer. EDD = retrieval + 266 days.
Baby at week 13
At 13 weeks gestational after IVF transfer: Fingerprints form. Placenta takes over hormone production from the corpus luteum. Vocal cords develop further.
Mother's body — what changes
Post-IVF at week 13, clinical picture: Second trimester begins. Many symptoms ease. Visible bump for second-time mothers.
Nutrition & supplements
Focus on folic acid 400–600 mcg/day (neural tube), iodine 150 mcg, and small frequent meals to counter nausea. No extra calories yet — normal maintenance intake is adequate. Post-IVF continue progesterone support and prenatal vitamin exactly as your REI prescribed. Do not add herbal supplements without clearance — many interact with luteal support.
Safe exercise
150 minutes/week of moderate activity — brisk walking, stationary cycling, prenatal yoga. Stop any exercise that leaves you unable to hold a conversation. After IVF avoid high-impact activity until confirmed viability at 8-week scan. Then follow standard trimester guidance.
Doctor visit checklist — week 13
- ✓Second trimester begins — schedule anatomy scan for weeks 18–22
- ✓Progesterone support review — continue until placenta takeover (week 10–12)
- ✓Beta-hCG doubling every 48–72 hours until viability scan
- ✓First IVF viability ultrasound at 6–7 weeks gestational
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
- ⚠Sudden loss of pregnancy symptoms + spotting
- ⚠Severe one-sided pain (ectopic pregnancy signal)
Week 13 — Frequently asked questions
How accurate is the IVF Pregnancy Calculator at week 13?
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 13?
Approximately the size of a pea pod — length 7.4 cm and weight 23 g. These are median values from ASRM, SART and ESHRE references.
Which symptoms are normal in week 13?
Second trimester begins. Many symptoms ease. Visible bump for second-time mothers. Every pregnancy is different — call your provider if anything on the warning-signs list appears.
Should I have an ultrasound at week 13?
Second trimester begins — schedule anatomy scan for weeks 18–22. Routine scan windows are: dating (10–13w), anatomy (18–22w), growth (28–32w).
How much weight should I gain by week 13?
Approximately 1.9 kg cumulative if you started at a normal BMI (IOM guideline). Underweight mothers gain more; overweight mothers less.
Day 3 vs Day 5 transfer at week 13 — what's the difference?
Day-5 blastocyst transfer adds 5 days to embryo age; Day-3 transfer adds 3 days. Gestational age = transfer date + (14 − transfer day) days + weeks since transfer. Both converge on the same due date; the difference matters only in the first 2 weeks.
Should I continue progesterone at week 13?
Most REI clinics wean progesterone by week 12. Follow your clinic's exact taper — abrupt stop before placental takeover risks miscarriage.
Content aligned with ASRM, SART and ESHRE. 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.