22 weeks pregnant: baby is the size of a sweet potato

Your baby this week

Your baby's lips are more distinct, and the eyebrows and eyelashes are visible. Taste buds are forming on the tongue, and your baby swallows amniotic fluid that carries flavours from what you eat. Research suggests that babies may learn about flavours in the womb, although this does not mean your diet controls your baby's tastes.

Your baby also has a sense of touch, and may explore the face, cord and the walls of the womb with the hands. The pancreas is developing, and the lungs are growing branches, though they are not ready for breathing air.

How it happens. Flavours from your food pass into your blood and then into the amniotic fluid in small amounts. Your baby swallows the fluid many times a day, and this is a form of early sensory experience.

Your body this week

Your uterus is a little above your belly button, and your bump is growing faster than before. The skin on your belly, breasts, hips and thighs is stretching. Your hormones are also changing how your skin behaves, so it may be dry, oily, itchy or pigmented in new places.

Your weight is going up steadily, and your appetite is strong. If your skin feels different, you are not alone.

Stretch marks

Stretch marks, called striae, are narrow bands that appear when the deeper layers of skin stretch quickly. They start red, pink or purple and usually fade to a lighter, silvery colour after birth.

Why some people get them and others do not. Genes are the strongest factor. If your mother or sisters had them, you are more likely to. Rapid weight gain, a bigger baby, twins and hormone changes can also contribute. It is not a sign that you did anything wrong.

Can you prevent them? Evidence that creams, oils or lotions prevent stretch marks is weak, and no product has been shown to work reliably. That does not mean moisturizing is pointless. It can ease dryness and itching, and many people find it comforting. Drinking water and gaining weight gradually may help skin adapt, but they do not guarantee that you will avoid marks.

What about treatment? Most marks fade over months to years. If they bother you after birth, dermatologists can discuss options, but do not use retinoid creams during pregnancy or breastfeeding without medical advice.

Itchy skin: usually harmless, sometimes not

Mild itching is common, especially over the stretching belly. Try:

• Moisturizing twice a day with a fragrance-free product.
• Lukewarm showers instead of hot ones.
• Loose cotton clothing.
• Oatmeal-based bath products if your skin is dry.

Some pregnancy-specific rashes also occur. One example is PUPPP (pruritic urticarial papules and plaques of pregnancy), an itchy rash of small red bumps, often beginning in stretch marks on the belly. It is uncomfortable but harmless to your baby, and providers can suggest treatments. Ask your provider about any new rash.

The itch that needs a same-day call

A less common condition, obstetric cholestasis (also called intrahepatic cholestasis of pregnancy), is a liver condition in which bile acids build up in the blood. Its main symptom is itching, and it has a typical pattern:

• Itching without a rash. The skin looks normal, but feels intensely itchy.
• Palms of the hands and soles of the feet. These are often affected first, though it can be anywhere.
• Worse at night. It can keep you awake.
• It may come with dark urine, pale stools or yellowing of the skin or eyes.

It usually appears in the third trimester but can start earlier. It is treatable, but it can raise the risk of complications for your baby, so a blood test (for liver function and bile acids) is needed. If you have this kind of itch, call your provider or maternity unit the same day. Do not wait for your next appointment.