From the Guidelines
The first invasion of trophoblast cells in pregnancy occurs around 8-10 weeks of gestation. During this process, extravillous trophoblast cells from the developing placenta invade the maternal decidua and spiral arteries 1. This initial invasion is crucial for proper placental development and establishment of maternal-fetal circulation. The trophoblast cells remodel the maternal spiral arteries, transforming them from high-resistance, low-flow vessels into low-resistance, high-capacity vessels. This transformation ensures adequate blood flow to the developing fetus. A second wave of trophoblast invasion typically occurs around 16-18 weeks, extending deeper into the myometrium. Inadequate trophoblast invasion during these critical periods has been associated with pregnancy complications such as preeclampsia, intrauterine growth restriction, and placental insufficiency 1. The timing and success of this invasion process are regulated by complex interactions between maternal immune cells, decidual cells, and the invading trophoblast.
Some key points to consider:
- The invasion of trophoblast cells is a critical step in placental development and maternal-fetal circulation establishment.
- Abnormalities in trophoblast invasion have been linked to pregnancy complications such as preeclampsia and placental insufficiency.
- The process of trophoblast invasion is regulated by complex interactions between maternal and fetal cells.
- Understanding the timing and mechanisms of trophoblast invasion can provide valuable insights into the development of pregnancy complications and the establishment of effective preventive and therapeutic strategies.
It is essential to note that the provided evidence 1 highlights the importance of trophoblast invasion in pregnancy and its association with pregnancy complications. However, the exact mechanisms and timing of this process may vary depending on individual factors and require further research for a more comprehensive understanding.
From the Research
Trophoblast Invasion in Pregnancy
- The first invasion of trophoblast in pregnancy occurs during the implantation of the embryo, which typically happens around 6-12 days after fertilization, but the exact week of trophoblast invasion is not specified in the provided studies.
- However, it is mentioned that deep trophoblast invasion into the maternal decidua is a particular feature of human pregnancy, and this invasion needs to be finely regulated to allocate resources between mother and baby 2.
- The studies suggest that trophoblast invasion is a complex process that involves the invasion of specialized fetal extravillous trophoblasts into the maternal uterus, and this process is crucial for the establishment of a successful pregnancy 3, 4, 5, 6.
Timing of Trophoblast Invasion
- While the exact week of trophoblast invasion is not specified, it is known that trophoblast invasion occurs during the first trimester of pregnancy, and abnormalities in this process can lead to pregnancy complications such as pre-eclampsia, fetal growth restriction, and stillbirth 2, 3, 4, 5, 6.
- The invasion of endoglandular trophoblast into uterine glands starts at the time of implantation, followed by invasion of endovenous trophoblasts into uterine veins, and finally, invasion of endoarterial trophoblasts into spiral arteries takes place, enabling hemotrophic nutrition of the fetus starting with the second trimester of pregnancy 4.