The projections branch and rebranch in a complicated treelike arrangement. This arrangement greatly increases the area of contact between the wall of the uterus and the placenta, so that more nutrients and waste materials can be exchanged.
The placenta is fully formed by 18 to 20 weeks but continues to grow throughout pregnancy. At delivery, it weighs about 1 pound. Merck and Co. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world. The Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge.
This site complies with the HONcode standard for trustworthy health information: verify here. Common Health Topics. Development of the Blastocyst. Development of the Embryo. Development of the Fetus and Placenta. Normal Pregnancy. Test your knowledge. Maternal infections that develop after the delivery of a baby usually begin in the uterus. The likelihood of developing a uterine infection is increased with which of the following types of delivery?
More Content. Click here for the Professional Version. From Egg to Embryo Once a month, an egg is released from an ovary into a fallopian tube. Placenta and Embryo at About 8 Weeks At 8 weeks of pregnancy, the placenta and fetus have been developing for 6 weeks. Allows materials to be exchanged between the blood of the mother and that of the embryo. The embryo floats in fluid amniotic fluid , which is contained in a sac amniotic sac. Provides a space in which the embryo can grow freely.
By 12 weeks of pregnancy: The fetus fills the entire uterus. By about 24 weeks: The fetus has a chance of survival outside the uterus. Was This Page Helpful? Yes No. Physical Changes During Pregnancy. Development of the Fetus.
Overview of the Postdelivery Postpartum Period. Hepatocellular Carcinoma. In general, once the fertilized egg implants in the uterine wall, the placenta begins forming. But the ball starts rolling several days before implantation. When you ovulate, an egg leaves the ovary to travel through the fallopian tube in hopes of being fertilized. If successful, the ovulated egg meets up with a spermatozoid to begin formation of the fetus.
This ovulated egg is called a zygote. Over the course of a few days, the zygote will complete many cell divisions in the fallopian tube. When the zygote reaches the uterus, these cell divisions continue, and then the zygote becomes a blastocyst.
At this stage, some cells begin to form into the placenta and others begin to form the fetus. The blastocyst embeds in the endometrium aka implantation. To help support pregnancy, the placenta produces a hormone called human chorionic gonadotropin hCG.
Over the course of your pregnancy, the placenta grows from a few cells into an organ that will eventually weigh about 1 pound. By week 12, the placenta is formed and ready to take over nourishment for the baby.
However, it continues to grow throughout your pregnancy. Under normal conditions, the placenta will attach to the wall of your uterus. As pregnancy progresses, it will move with your growing uterus. Although each pregnancy is different, you can expect the placenta to take over around weeks 8 to 12 of pregnancy, with 10 weeks being the average time for most women.
Those who get pregnant via in vitro fertilization or have hormone deficiencies may need progesterone supplementation in the first trimester. These individuals are often able to stop taking this hormone once the placenta begins its own production. Many women look forward to the second trimester — energy levels rise, hormone levels begin to balance out, and morning sickness subsides. But why does everything seem to get better?
As already mentioned, towards the end of the first trimester around week 10 , the placenta takes over the production of progesterone. This helps reduce nausea and vomiting. For many mamas, this means an end to morning sickness. The placenta may play a role in that case, too. If you happen to have a higher concentration of a protein called GDF15 in your blood, those frequent bouts of nausea and vomiting may continue for some time.
One study found that women who reported vomiting in the second trimester had a higher level of maternal circulating GDF15 concentrations around week 15 of pregnancy. The good news? Researchers speculate that high levels of GDF15 could mean that the placenta is developing properly. The placenta usually attaches to the side or at the top of the uterus, but this is not always the case.
Sometimes, it can develop in the wrong location or attaches too deeply, leading to placenta disorders. Even if you experience a healthy pregnancy, complications with the placenta can still occur.
What to Expect follows strict reporting guidelines and uses only credible sources, such as peer-reviewed studies, academic research institutions and highly respected health organizations. Learn how we keep our content accurate and up-to-date by reading our medical review and editorial policy.
The educational health content on What To Expect is reviewed by our medical review board and team of experts to be up-to-date and in line with the latest evidence-based medical information and accepted health guidelines, including the medically reviewed What to Expect books by Heidi Murkoff. This educational content is not medical or diagnostic advice. Use of this site is subject to our terms of use and privacy policy. Registry Builder New.
What Is the Placenta? Medically Reviewed by Jennifer Wu, M. Medical Review Policy All What to Expect content that addresses health or safety is medically reviewed by a team of vetted health professionals. Getty Images. Your baby is just half of what your doctor checks during routine ultrasounds. That's because you're not just growing a baby — you're growing a one-stop shop for all your baby's needs: the placenta.
Back to Top. In This Article. What is the placenta? What does the placenta do? Continue Reading Below. More on Your Baby's Placenta. What Is an Anterior Placenta? Eating the Placenta.
Placenta Previa. View Sources. Fetal Health. Pregnancy Groups. Jump to Your Week of Pregnancy. Pregnancy Week.
0コメント