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The Beautiful Placenta

While your baby grows and matures over nine months of pregnancy, there’s something else growing in your uterus too — and it’s responsible for keeping your baby alive. You’ve likely heard of the placenta, but what does it do? Here’s what you need to know about your placenta to have a healthy pregnancy.

What is the placenta?

The placenta is a pancake-shaped organ that develops in the uterus exclusively during pregnancy. It comprises blood vessels and provides your

growing baby with nutrients, water, oxygen, antibodies against diseases, and a waste removal system. The placenta attaches to the uterine wall and connects to your baby via the umbilical cord. It also contains the same genetic material as your baby.

What does the placenta do?

The placenta is the lifeline between your baby and your own blood supply. Through all stages of pregnancy, it lets your baby eat and breathe — with your help, of course.

As your own blood flows through your uterus, the placenta seeps up nutrients, immune molecules, and oxygen circulating through your system. It shuttles these across the amniotic sac, through the umbilical cord to your baby, and into his blood vessels. Likewise, your baby passes carbon dioxide and other waste he doe

sn’t need back to you via the placenta. The placenta also acts as a barrier. It’s vital that germs in your body don’t make your baby sick and that your body doesn’t reject your baby as a foreign “intruder.” At the same time the placenta allows blood cells and nutrients through, it keeps most (but not all) bacteria and viruses out of the womb. It also prevents many of your baby’s cells from entering your bloodstream, where they might set off alarms.

In recent years, scientists have discovered that your placenta has even more functions than they’d known about in the past. Rather than just being a passive bridge between you and your baby, the placenta also produces hormones and signaling molecules, such as human placental lactogen (HPL), relaxin, oxytocin, progesterone,

and estrogen, which you both need during pregnancy.

Some of these molecules encourage new blood vessels to form — both between your body and the placenta, and between the placenta and your baby — to carry oxygen to the fetus. Some help your body prepare to make milk (but also prevent you from lactating before you give birth). Some boost your metabolism to help supply energy to both you and your growing baby.

When does the placenta form?

The placenta starts developing very early on in pregnancy at about week 4. Seven or eight days after a sperm fertilizes an egg, a mass of cells — the earliest form of an embryo — implants into the wall of the uterus.

Some cells from this mass split away, burrowing deeper into the uterine wall. Instead of preparing to form fingers, toes, and other body parts like the rest of the embryo’s cells, these ones will form the placenta.

Over the next two months, the placenta develops. Small capillaries turn into larger vessels, providing your growing baby with more oxygen and nutrients. As you near the second trimester, the placenta will have completed its Herculean development.

When does the placenta take over?

Between weeks 10 to 12 of pregnancy, your placenta takes over from a structure known as the corpus luteum. It'll sustain your baby for the rest of pregnancy — and continue to grow larger as your baby grows.

For most of the first trimester, the corpus luteum performs the placenta’s essential functions while the organ gets up to the task. The corpus luteum is a collection of cells that produce progesterone and some estrogen. It forms every month after you ovulate in the follicle that releases the egg during that cycle.

If you’re not pregnant, the corpus luteum disintegrates about 14 days after ovulation, triggering your period. When you are pregnant, the structure continues to grow and produce hormones to support your little embryo until

the placenta takes over.

Forming a brand-new organ takes loads of energy and contributes significantly to first-trimester pregnancy fatigue. That’s one reason you can expect to feel more energized in the second trimester after the placenta has formed.

For more, visit What to Expect

Have you done anything special with your placenta following childbirth? Encapsulation, tincture, special burial...there are several options for handling this amazing childbirth organ!


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