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Week 4

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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!

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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.

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Summer 2014: Good Growing Newsletter

In This Issue

  • Understanding the Power and Influence of Role Models
  • Legal Marijuana Means Greater Poisoning Risks for Children
  • Why Choose Pediatric Emergency Care?

Download Summer 2014 (PDF)

Videos

Miracle Makers 2014 3:07:00Expand
6.6.14

The 30th annual Miracle Makers fundraising special aired on KOMO 4 TV on June 6, 2014. The special takes us on a journey through the hopes, fears, victories and challenges facing patients at Seattle Children's. Cosponsored by Costco Wholesale and KOMO 4. 

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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.

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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