What causes bleeding of fetal membranes?

During pregnancy, a woman's body will undergo some changes as the fetus grows. In addition to paying more attention to her physical health, pregnant women also need regular prenatal checkups to observe the development of the fetus in a timely manner. Amniotic membrane bleeding is a phenomenon of premature birth after pregnancy. If amniotic membrane bleeding occurs, the fetus needs to be protected in time. It is not advisable to get out of bed and move around, and you need to stay in bed and rest.

What causes bleeding of fetal membranes?

It is considered to be a precursor to miscarriage, which may be related to fatigue and weak physical constitution. It is recommended to rest in bed and take oral medication to preserve the pregnancy.

Fetal membrane composition

Amnion and chorion

When the embryonic body folds are formed, the extraembryonic ectoderm surrounding the embryonic disc and the extraembryonic body wall mesoderm fold upward into the embryonic body, and finally converge on the dorsal side of the embryonic body to form the amnion, which encloses the fetus inside and the chorion on the outside.

Yolk sac

Due to the formation of body folds, the archenteron is constricted into two parts, namely the archenteron inside the embryo and the yolk sac outside the embryo. The yolk sac gradually shrinks and degenerates later.

Allantoic sac

The allantois develops from a blind sac that protrudes outward from the ventral side of the end of the hindgut, gradually expanding to the extraembryonic body cavity and surrounding the amniotic membrane. Later, the outer wall of the allantois is closely attached to the chorion to form the chorioallantoic membrane, which is closely connected with the endometrium to form the basis of the placenta. After the fetus is born, the allantois stalk is closed to form the bladder ligament.

Umbilical cord

The umbilical cord is a cord-like structure connecting the navel of the embryo to the placenta. The umbilical cord is covered with amniotic membrane and contains the yolk sac pedicle, allantois, umbilical artery and umbilical vein. Two umbilical arteries transport the embryo's blood to the placental villi. The fetal blood in the villi capillaries exchanges substances with the maternal blood in the intervillous spaces. An umbilical vein transports the blood collected in the placental villi back to the fetus. The umbilical cord of a full-term fetus is approximately the same length as the fetus, about 40-60cm, about 1.5-2.0cm thick, with an average length of 55cm. The umbilical cord length of more than 100 cm accounts for about 1%. It has been reported in the literature that the longest umbilical cord is 300cm. The length of the umbilical cord is related to the amount of amniotic fluid and the activity of the fetus in the amniotic fluid. If the fetus is more active, the umbilical cord is generally longer.

The umbilical cord is an important channel and the only bridge for substance exchange between the embryo and the mother. Umbilical cord blood transports rich oxygen and nutrients to the fetus, and sends metabolic waste and carbon dioxide to the placenta, which seeps into the mother's blood and is excreted from the body.

If the umbilical cord length is less than or equal to 30cm, it is called a short umbilical cord, and its incidence is about 1%. An umbilical cord that is too short can cause difficult delivery, or cause early placental abruption, or rupture of the umbilical cord blood vessels, resulting in excessive bleeding and serious consequences.

If the umbilical cord length is equal to or greater than 70cm, the umbilical cord is too long. An umbilical cord that is too long can easily get wrapped around the fetus' neck or limbs. The incidence of umbilical cord around the neck is approximately 17%. It can wrap around the neck up to 8 times, causing local dysplasia and in severe cases leading to suffocation or death of the newborn.