week-4-feature-Weeks 4-6_1
Pregnancy Week 4
Discover your baby's latest fetal developments in week four of your pregnancy and get tips on sharing the exciting news with your friends and family.
How Big is Baby?
Your fertilized egg, known as a zygote, is a ball of 32 cells that's about the size of a poppy seed. It's at this stage that the cells separate into three distinct layers from which your baby's internal organs and skin will develop.
Baby's Length: 0.01in.
Baby's Weight: 0.04oz.
Mom's Changing Body
You just missed your period and the test came back positive—that's right, you're pregnant! Can't bear to fasten your bra in the morning? For most women, breast tenderness is the first physical sign of pregnancy—even before telltale morning sickness strikes. (If your breasts aren't sore now, odds are they will be within a few days or weeks.) You may also experience more extreme senses of taste and smell. In other words, that vase of peonies has never smelled better, but your coworker's tuna sandwich—which he's eating three cubicles away—might make you beeline for the bathroom.
Baby's Development
So what's going on in your womb this week? Your embryo may be minuscule, but trust us: Super-important developments are already under way. This week the embryo splits into two parts. One half will become the placenta, a special tissue that delivers must-have nutrients and oxygen to your baby throughout your entire pregnancy. In the other half, the embryo itself continues to grow, and a sheet of cells has just begun to create the neural tube, where your baby's brain, spinal cord and backbone will ultimately form.
Weekly Tip
Don't be surprised if your doctor doesn't schedule an appointment to see you until your 8- to 12-week mark. Many healthcare practices have potential mommies-to-be come in for a blood test with a nurse first to confirm pregnancy and then wait until you're far enough along to better estimate your due date through an ultrasound test.
Week 4 Ultrasound
The small circle at the center of the sonogram may not look like much, but that little sac is a kind of baby cocoon called a gestational sac. The cells that make up this sac will begin to specialize. Some cells will become part of the placenta. Some will form the amniotic sac that will fill with fluid to cushion your developing baby. Other cells are destined to form everything from delicate eyelashes to muscles and skin. But that's still a long way away.
Credit:
American Institute of Ultrasound in Medicine - AIUM.org
What Week 4 of Your Pregnancy Is Really Like
This Week's To-Do List
This Week's FAQs
Must-Reads
Related Content
-
-
Is It Implantation Bleeding or Your Period? Here's How to Tell
What does implantation bleeding look like? Medical experts explain how to tell if your spotting is an early sign of pregnancy or your monthly menstrual cycle. -
Which Medications Are Safe During Pregnancy?
Wondering which medications are safe for pregnant women to take? From Advil to Tylenol, Tums to Pepto, here’s your cheatsheet when it comes to the most common conditions you may need to treat while you're expecting. -
7 Reasons for a Late Period That Don't Mean You're Pregnant
A menstrual cycle that's off schedule doesn't always mean you're pregnant. Here are seven other reasons your period could be late. -
This Is How I Knew I Was Pregnant
We asked Parents staff members to share their first signs of conception, since early pregnancy symptoms differ for everyone.
