IVF Pregnancy Calculator — Week 18 (Day 3 & Day 5 Transfer)
You are 18 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.
How to Use This Calculator
1. Enter the retrieval date
Use the labelled fields and units that match your situation.
2. Calculate instantly
The result, visual comparison, and working update as values change.
3. Discuss the estimate with your clinician
Check assumptions, then copy, print, or share the calculation.
Practical Examples & Use Cases
| Starting date | Method | Calculation | Planning use |
|---|---|---|---|
| 1 Jan | Retrieval | +266 days | Estimated due date |
| Known clinical date | Ultrasound | Clinician dating | Confirm or revise estimate |
Baby at week 18
At 18 weeks gestational after IVF transfer: Ears reach final position on head. Uterus grows rapidly. Meconium accumulates in bowel.
Mother's body — what changes
Post-IVF at week 18, clinical picture: Baby movements more consistent. Braxton-Hicks contractions may start (painless tightening).
Nutrition & supplements
Add ~340 kcal/day above pre-pregnancy baseline. Prioritise iron (27 mg/day), calcium (1000 mg), omega-3 DHA (200–300 mg) and 71 g protein. Continue prenatal vitamin. 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
Continue 150 min/week. Avoid supine (flat-on-back) exercises after week 20 — they compress the vena cava. Swimming and prenatal Pilates are ideal now. After IVF avoid high-impact activity until confirmed viability at 8-week scan. Then follow standard trimester guidance.
Doctor visit checklist — week 18
- ✓Anatomy ultrasound (18–22 weeks) — check all organs and placenta location
- ✓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 gush of fluid (early rupture of membranes)
- ⚠Absent fetal movement for 12+ hours after 24 weeks
- ⚠Severe headache + visual disturbance (preeclampsia)
Week 18 — Frequently asked questions
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.
Related Calculators & Tools
Pregnancy Calculator
Week 18 guidance and calculation for this pregnancy timeline.
Twin Pregnancy Calculator
Week 18 guidance and calculation for this pregnancy timeline.
Pregnancy Countdown Calculator
Week 18 guidance and calculation for this pregnancy timeline.
Conception Calculator
Week 18 guidance and calculation for this pregnancy timeline.
IVF Pregnancy Calculator — Week 17
Review the previous week in this pregnancy timeline.
IVF Pregnancy Calculator — Week 19
Continue to the next week in this pregnancy timeline.