Skip to main content

Search
Safety and Wellness

Week 4

|

Your Baby's Development

Pregnancy Calendar

Four weeks into your pregnancy, your baby (called an embryo) consists of two layers of cells — the epiblast and the hypoblast — that will eventually develop into all of your baby's organs and body parts. Two other structures that develop at this time are the amnion and the yolk sac. The amnion, filled with amniotic fluid, will surround and protect the growing embryo. The yolk sac will produce blood and help to nourish the embryo until the placenta takes over that role.

Week 4

Your Body

This week your baby continues to implant in your uterus, burying itself deep within the endometrium. Once implanted, your baby starts to produce a hormone called human chorionic gonadotropin (hCG), which helps to maintain the lining of the uterus. It also sends a signal to the ovary to stop releasing an egg each month, which stops your monthly periods. Some women experience slight cramping and spotting of blood during this week while implantation is taking place, and they may mistake this for a period, as it often occurs around the time their monthly period was due.

hCG is the hormone that is measured in pregnancy tests. This week a pregnancy test will probably be able to detect your pregnancy! hCG also causes the symptoms of pregnancy, which can appear this week. Fatigue, tingling or aching breasts, or nausea might lead you to believe your period will be starting any day because the first pregnancy symptoms resemble premenstrual syndrome (PMS). But by the end of this week, your expected period will not take place. Your pregnancy is well on its way!

View All Previous Next

License

Note: All information is for educational purposes only. For specific medical advice, diagnoses and treatment, consult your doctor.

© 1995–2014 The Nemours Foundation/KidsHealth. All rights reserved.

Should your child see a doctor?

Find out by selecting your child’s symptom or health condition in the list below:

Spring 2014: Good Growing Newsletter

In This Issue

  • Cold Water Shock Can Quickly Cause Drowning
  • E-Cigs Are Addictive and Harmful
  • Bystanders Can Intervene to Stop Bullying

Download Spring 2014 (PDF)

Videos

Overcoming the Odds: A KING 5 TV Children's HealthLink Special 0:44:45Expand
12.30.13

In the spirit of the holidays, patients, parents and doctors share inspirational stories of healing and hope. From surviving heart failure and a near-death drowning to battling a flesh-eating disease, witness how the impossible became possible thanks to the care patients received at Seattle Children's Hospital.

Play Video
Miracle Season 2013 0:57:06Expand
12.11.13

Miracle Season, hosted by Steve Pool and Molly Shen, aired Dec. 8, 2013, on KOMO 4 TV. The annual holiday special celebrates the remarkable lives of Seattle Children's patients.

Play Video
Children’s Mental Health 0:00:30Expand
11.22.13

Mark Fadool, clinical director of mental health services at Odessa Brown Children's Clinic, provides early warning signs of mental health issues in kids and teens and urges us all to notice the signs and act early.

Play Video