Twin Pregnancy Calculator — Week 11: Di/Di, Mo/Di & Mo/Mo
You are 11 weeks pregnant with twins. Twin gestation deviates meaningfully from singleton pregnancy from week 11 onwards — chorionicity, growth discordance and delivery timing all change. Here is the exact week-11 twin picture.
Twin Pregnancy Calculator
Enter the first day of your last menstrual period (LMP). EDD = LMP + 280 days.
Baby at week 11
Per twin, week 11 development: Fetal breathing movements begin as diaphragm develops. Head is still half of body length. Fingers unwebbed; can open and close.
Mother's body — what changes
Twin pregnancy at week 11 differs — expect: Nausea usually starts easing. Areolas darken. Linea nigra may appear on abdomen.
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. For twin gestation add an extra 300 kcal on top (total ~600 second trimester, ~750 third), 50% more iron, and split hydration to 3–3.5 L/day.
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. For twins reduce intensity 20% earlier — bed rest is not routinely indicated but modified activity from week 24 is prudent.
Doctor visit checklist — week 11
- ✓NT scan (nuchal translucency) window: 11+0 to 13+6 weeks
- ✓Chorionicity confirmed at 10–14 weeks (Di/Di, Mo/Di, or Mo/Mo)
- ✓Growth scans every 4 weeks (Di/Di) or every 2 weeks (Mo/Di, TTTS surveillance)
- ✓Maternal-fetal medicine (MFM) referral by week 20
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 11 — Frequently asked questions
How accurate is the Twin Pregnancy Calculator at week 11?
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 11?
Approximately the size of a fig — length 4.1 cm and weight 7 g per twin (combined weight roughly 1.8× singleton for well-nourished mothers). These are median values from SMFM, ACOG twin guidelines and NICE multiple pregnancy references.
Which symptoms are normal in week 11?
Nausea usually starts easing. Areolas darken. Linea nigra may appear on abdomen. Every pregnancy is different — call your provider if anything on the warning-signs list appears.
Should I have an ultrasound at week 11?
NT scan (nuchal translucency) window: 11+0 to 13+6 weeks. Routine scan windows are: dating (10–13w), anatomy (18–22w), growth (28–32w).
How much weight should I gain by week 11?
Approximately 1.6 kg cumulative if you started at a normal BMI (IOM guideline). Underweight mothers gain more; overweight mothers less. Twin gestation targets 16–24 kg total (higher than singleton 11–16 kg).
Is my twin pregnancy Di/Di, Mo/Di or Mo/Mo?
Chorionicity is confirmed on the 10–14 week ultrasound by looking at the membrane between twins — 'lambda sign' = Di/Di (safest), 'T sign' = Mo/Di (requires TTTS monitoring every 2 weeks), no membrane = Mo/Mo (highest risk, delivery by 34 weeks).
When are twins usually delivered?
Di/Di twins: 38 weeks. Mo/Di twins: 36–37 weeks. Mo/Mo twins: 32–34 weeks by planned C-section. About 60% of twins deliver preterm (<37 weeks) spontaneously.
Content aligned with SMFM, ACOG twin guidelines and NICE multiple pregnancy. 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.