Pregnancy Week 5

Learn what is happening with your baby's development in week five. Plus, learn about miscarriage, changes in your complexion, and what healthy foods you should be eating now.

Week by week baby size image. Week by week baby size image.

How big is baby?

The ball of cells now resembles a tadpole and is as big as a peppercorn. The creation of the brain, spinal cord, heart, and blood vessels is already well under way.

Baby's Length: 0.05in.
Baby's Weight: 0.04oz.
Fetus at Week 5 What the baby looks like at week 5 of fetal development. Med ART Studios Explore More

Baby's Development

This week, your baby's ticker will start beating for the first time! (Neither you nor your doctor can hear it yet, but it may be possible to see the movement on an ultrasound.) And your little one has been really busy growing! The embryo now has three distinct layers: the outer ectoderm, which will form the nervous system, ears, eyes, inner ear and many connective tissues; the endoderm, or inner layer, which will grow into internal organs like the lungs, intestines and bladder; and the middle mesoderm, which will eventually make way for the heart and circulatory system. In the weeks to come, the mesoderm will also evolve into bones, muscles, kidneys and reproductive organs.

Baby Week 5

Close
Pregnancy-related symptoms may begin at this stage. These include nausea, fatigue, increased urinary frequency, and tender breasts. It may also be normal to experience no symptoms at this stage.The growing embryo is still only about the size of an apple seed and is shaped like a small tadpole.Within the embryo, the heart is starting to divide into chambers and tiny cardiac cells are beginning to contract.Once derived from a yolk sac, oxygen and nutrients will soon be delivered from the uterus to the embryo by the umbilical cord.
Week by week baby ultrasound image. Week by week baby ultrasound image. American Institute of Ultrasound in Medicine - AIUM.org

Week 5 Ultrasound

The dark area is the fluid filling the gestational sac. Eventually, this fluid will be replaced by a sac containing the amniotic fluid your baby-to-be will live in for the next few months. The white circle within the fluid is called the yolk sac. Before the placenta is fully formed, the yolk sac plays a role in providing all the nutrients your baby-to-be needs to grow. Adjacent to the yolk sac, little + marks show a very early embryo. The sonographer measures the length of the embryo (the crown-rump length or CRL) to confirm or revise the due date estimated from your LMP, or to evaluate the embryo's growth.

Read More

Watch Baby's Growth

An Embryo Forms: Weeks 4 to 8 of Pregnancy

Mom's changing body

Feeling overjoyed one minute and equally stressed out the next? It's all part of the normal mood swings that come along with pregnancy. You might feel elated, depressed, angry, sentimental, powerful, and insecure -- sometimes all in the same hour. Your hormones are flaring, so it's only natural for emotions to do the same, especially when a major life change is on the way. Mood swings are often the most intense during the next month, and they sometimes surge again toward the end of pregnancy. Also, you may be surprised to learn that about 10 to 12 percent of women will experience depression during pregnancy -- nearly as many as those who do postpartum. If at any point during your pregnancy you feel depressed for more than two weeks, call your practitioner.

Weekly Tip

No matter how you're feeling, remember that getting enough sleep is a sure mood-booster. Eight hours or so of shut-eye can make a world of difference. And right now, you might feel like dozing off all the time -- at work, in front of the TV, in mid-sentence -- thanks to soaring progesterone levels, lower blood sugar, lower blood pressure, and increased blood volume.

This Week's To-Do List

Must-Reads

An Embryo Forms: Weeks 4 to 8 of Pregnancy

Chances are you have no idea you're pregnant yet-but your body is already hard at work. Watch as the egg undergoes its wondrous transformation to embryo.

Your Developing Baby: Week 5

What's going on with your baby in his fifth week in utero? Learn all about fetal development and important pregnancy milestones specific to this week of pregnancy!

The Inside Story: Your Baby in Week Five

Find out what's happening with your growing baby's fetal development during her fifth week of pregnancy.

Your Pregnancy: 5 Early Pregnancy Symptoms Most Women Deal With

What are the five most common early pregnancy symptoms? Dr. Obosa Osawe's here to explain.

Q&A: Prescription Medication during Pregnancy

If you're curious about what prescription medications will be safe for you and baby, be sure to speak with your doctor.