Pregnancy Countdown — 21 Weeks Left Until Due Date
You have 21 weeks left until your estimated due date (EDD). That means you are currently around week 19 of pregnancy. Below is a countdown-focused plan — what to prepare, what to pack and which milestones you should hit this week.
Pregnancy Countdown Calculator
Enter the first day of your last menstrual period (LMP). EDD = LMP + 280 days.
Baby at week 21
With 21 weeks left, your baby has already: Rapid brain growth. Digestive system produces meconium. Fetus responds to sound with movement.
Mother's body — what changes
With 21 weeks to go, your body is: Varicose veins may appear. Heartburn common as uterus pushes stomach up.
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. With only 21 weeks left, focus on iron-rich foods to build baby's stores for the first 6 months of life, and vitamin K-rich leafy greens.
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. With 21 weeks left, prioritise perineal massage, pelvic tilts and squats — active preparation for the pushing stage.
Doctor visit checklist — week 21
- ✓Start iron supplement if hemoglobin <11 g/dL
- ✓Weekly antenatal visit from week 36
- ✓Group B Strep swab at 35–37 weeks
- ✓Discuss induction/C-section timing at 39–40 weeks
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 21 — Frequently asked questions
How accurate is the Pregnancy Countdown Calculator at week 21?
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 21?
Approximately the size of a carrot — length 26.7 cm and weight 360 g. These are median values from NHS antenatal guidance and ACOG term-delivery references.
Which symptoms are normal in week 21?
Varicose veins may appear. Heartburn common as uterus pushes stomach up. Every pregnancy is different — call your provider if anything on the warning-signs list appears.
Should I have an ultrasound at week 21?
Start iron supplement if hemoglobin <11 g/dL. Routine scan windows are: dating (10–13w), anatomy (18–22w), growth (28–32w).
How much weight should I gain by week 21?
Approximately 5.5 kg cumulative if you started at a normal BMI (IOM guideline). Underweight mothers gain more; overweight mothers less.
What should I pack 21 weeks before due date?
Hospital bag essentials: ID + insurance, birth plan, comfortable labour clothes, going-home outfit for baby (0–3M), 3 nursing bras, maternity pads, phone charger, snacks. Pack the bag by week 36 regardless of your 21-week countdown.
Signs of labour at 21 weeks to go?
Regular contractions <5 minutes apart lasting >60 seconds, waters breaking (gush or slow leak), bloody show (mucus plug + streak), and 4+ cm cervical dilation. Go to hospital when contractions are 5-1-1 (every 5 min, lasting 1 min, for 1 hour).
Content aligned with NHS antenatal guidance and ACOG term-delivery. 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.