Pregnancy Week 4 – Weekly Development

At last, at Week 4, you took a home pregnancy test and it came up positive, because the pregnancy hormone hCG (human chorionic gonadotropin) is present in your urine starting about ten days after conception.

You may sit staring in ecstasy at the two little lines on the pregnancy test, or you may have to take some time to get used to the idea of having a baby. Both responses are perfectly normal. Either way, you may not be feeling any different physically, because early pregnancy symptoms don’t always show up right away.

At 4 weeks, your baby is about the size of a single poppy seed.

Your Baby’s Development

At this nearly-microscopic stage, baby is known as a blastocyst, a tiny ball of cells that has implanted itself into the side of your uterus and will become an embryo. The cells will start to grow into different parts of baby’s body, such as the skeleton, muscles, nervous system, and organs.

The placenta, an organ that connects your body’s systems to the systems of the baby, attaches to the uterine wall where the blastocyst has implanted. The amniotic fluid, which cushions baby throughout your pregnancy, is already forming inside a yolk sac.

Your baby’s nervous system and heart are developing, and she already has some of her own blood vessels with blood starting to circulate. A string of blood vessels connects you to your baby, which will eventually become the umbilical cord.

Your Body & Symptoms

The onslaught of pregnancy hormones can cause symptoms similar to those you get before your period:

  • Mood swings. Pregnancy mood swings can be drastic during the first 12 weeks. The hormones level out by the second trimester.
  • Fatigue. A common symptom at 4 weeks pregnant is total exhaustion, as your body works so hard to turn that tiny blastocyst into an embryo.
  • Bloating. The pregnancy hormone progesterone may have you calling for your most comfortable pants and leggings.
  • Sore breasts. Another result of pregnancy hormones, telling your body to start preparing the milk ducts.
  • Mild cramping. Nothing to worry about. This is probably a sign that baby has properly implanted in the lining of your uterus.

It’s time to quit cigarettes and alcohol. Both can be harmful to your growing baby because the toxins pass through the placenta.

When you call your OBGYN to tell her you’re 4 weeks pregnant, she most likely will have you make your first prenatal appointment for a month later. If you’re healthy and at low risk for pregnancy complications, there’s no need to see your doctor yet. So relax, eat well, drink lots of water, take your prenatal vitamins. And look forward to seeing your baby’s heartbeat during your first prenatal exam at eight or nine weeks!

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