Week 06: Your pregnancy

Your baby's growth: Organs, eyes, limbs and more

Your baby is still very tiny … only about the size of a kidney bean. But this is a big week as organs and parts of the body begin to take shape.

Will your baby's eyes be brown, blue, green, or hazel? It's much too early to know, but by week six the eyes are beginning to develop and the earliest version of the retina is forming.

Here's what else is developing:

• Neural tube. The neural tube, which connects the brain and spinal cord, will close this week. This is good news because when the neural tube closes, your little one is much less likely to develop brain or spine defects such as spina bifida. However, it will be several weeks before the heartbeat can be heard with an instrument.
• Heart. Still located on the outside of the body, the heart is dividing into chambers and will find a more regular rhythm soon.
• Limbs. Upper and lower limb buds are forming on the body and will eventually develop into arms and legs.
• Brain. The brain begins to fill your baby's tiny skull.
• Larynx and inner ear.
• Neck and lower jaw. Below the opening that will later form your baby's mouth are small folds where the neck and the lower jaw will eventually develop.
• Facial features. As nostrils become distinct, facial features are already forming.
• Organs. The kidneys, liver, pancreas, lungs, stomach and intestines are developing.
• Placenta. The lining of the placenta develops. Its extensive blood flow structures provide the oxygen and nutrients your baby needs for its growth.

Fetal risks

Because the internal organs and limbs are in such an early stage of development, the embryo is sensitive to some drugs and viruses that might get past the placental barrier. Most birth defects begin between weeks four and eight of development—six to 10 weeks of pregnancy.

First movements

Halfway through this week the embryo will make her first movements, but you'll have to wait until your second trimester before you can actually feel your baby's wiggles.

What's happening with you

• Breast changes. Hormonal changes may cause your breasts to become larger and more sensitive. You may even be experiencing tingling sensations and the areola may start to darken.
• Weight change. You may have gained two or three pounds. But if you've been experiencing morning sickness, you may actually have lost some weight.
• Morning sickness. If you're experiencing nausea, it may get worse this week as your hormone levels rise. Although it's called "morning sickness," it's perfectly normal for nausea to appear at any point of the day or night.

Protecting your baby

This is the time in your pregnancy when you'll need to be especially careful about toxins and infections. That's because your baby is especially vulnerable to birth defects in the first three months.

• Don't change your cat's litter. If you have a cat, ask a family member to change the litter to avoid risk of toxoplasmosis, an infection caused by parasites common in cat feces. It can be passed from Mom to baby.
• Check with your doctor before taking any medication— even those that you can buy without a prescription.
• Don't handle insecticides or other poisonous substances.