Day 151 of 280, second trimester
You are 21 weeks and 4 days
Your baby is making essential red and white blood cells faster than you do.
129 days until your due date
Stem cells in your baby's bone marrow make red and white blood cells and platelets (the cells that clump together to form clots). Earlier in pregnancy these were made in the yolk sac, then the liver and spleen, but now every bone contains red marrow that can make blood cells. Your baby's red blood cells last about 80 days before being removed, a faster turnover than yours, which last 120 days.
Bilirubin, a breakdown product of red blood cells, is produced in the liver and cleared from your baby's blood by the placenta. Your baby's liver takes a few days after birth to process bilirubin efficiently, so high levels can cause jaundice. If it develops, light therapy (phototherapy) breaks the bilirubin down into a form your baby can pass in urine.
As a newborn, your baby will be protected from infection by white blood cells and by antibodies in breast milk, especially colostrum. That's why breastfed babies have a lower risk of asthma, cow's milk intolerance, and food allergies.
Explainer
Ask about your records
If anything in your pregnancy records or test results is unclear, don't hesitate to ask your doctor to explain.
Good to know
Making sense of doctor's lingo
With more frequent appointments, it helps to understand the jargon in your records:
- Primigravida: first pregnancy. Multigravida: a later pregnancy.
- Hb: hemoglobin level. BP: blood pressure.
- Urine tests: NAD or nil means no abnormalities detected; P or alb means protein; Tr or + means a trace of sugar or protein; G means glucose.
- Heart rate and movement: FHH means fetal heart heard; FHHR, heard and regular; FMF or FMNF, fetal movements felt or not felt.
Your baby's position is described as the "presenting part" or "lie." The occiput is the back of the baby's head:
- LOT (left occipito-transverse): back and occiput on the left side of the uterus, at right angles to your spine.
- LOA (left occipito-anterior): back and occiput toward the front of the uterus on the left.
- LOP (left occipito-posterior): back and occiput toward your spine on the left.
- ROT (right occipito-transverse): back and occiput at right angles to your spine on the right.
- ROA (right occipito-anterior): back and occiput toward the front of the uterus on the right.
- ROP (right occipito-posterior): back and occiput toward your spine on the right.
Appointments and key dates around now
- Whooping cough vaccineUsually around 20 weeks, best before 32 weeks
Read the full 21 weeks pregnant guide
This is general information based on NHS guidance, not medical advice, and every pregnancy is different. Talk to your midwife or GP about anything that worries you. If your baby's movements slow down or change, or you have bleeding, severe pain or leaking fluid, call your maternity unit straight away. In an emergency, call 999.