You are 13 weeks and 2 days

Even this early, your baby has started to urinate, although in very small amounts.

187 days until your due date

Your baby's bladder now fills and empties every 30 minutes: she swallows amniotic fluid, filters it through her kidneys, and passes it as urine. Her bladder is tiny, holding only 10 ml even at 32 weeks and 40 ml by 40 weeks. Her urine is very dilute because her kidneys can't yet reabsorb much water, but the placenta does most of the kidneys' work until birth.

Your baby's blood can now form and break down clots. The placenta has been able to form clots for some time, reducing the risk of bleeding.

Your baby is making a small number of white blood cells but still relies on yours to fight infection. Her red blood cells contain hemoglobin, which carries oxygen around her body. Before birth she has several forms of hemoglobin that differ from yours: they're more stable at lower acidity and bind oxygen more easily, so her body can take oxygen from your hemoglobin.

Explainer

Toes

The toes are now fully formed and separate, and their individual bones can be clearly seen on an ultrasound.

Ask a Doctor

I'm expecting triplets. How will my prenatal care be different?

All the usual pregnancy risks are higher with more than one baby, partly because hormone levels are higher, and carrying and nourishing three babies is hard work for your body.

You'll be referred to an obstetrician who will plan your care with you, with more frequent checkups and scans. Many risks are outside your control, but if you go to all your appointments and look after your health, you're likely to have three healthy babies.

With triplets, you'll probably need a cesarean, and the average triplet pregnancy lasts 34 weeks. The National Organization of Mothers of Twins Clubs (nomotc.org) has information and local support groups.

Time to think about

Amniocentesis

Amniocentesis tests the amniotic fluid and is usually done at 16–18 weeks. It may be offered:

When there's a family or pregnancy history of a genetic problem.
To older women, who are at higher risk of a baby with a chromosomal abnormality.
When a screening test has shown a high risk of a chromosomal abnormality.

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.

Toes

I'm expecting triplets. How will my prenatal care be different?

Amniocentesis

Appointments and key dates around now