The placenta is an incredible organ, which protects and houses the growing and developing foetus over the pregnancy term. The health and efficiency of this organ is vital to your baby’s wellbeing.
The word “placenta” originates from the Greek word ‘plakous’ meaning flat cake, which gives an idea of what a placenta looks like.
The placenta attaches to the lining of the uterine wall (the womb) in the early weeks of pregnancy from the very early trophoblastic layer and grows alongside the developing foetus. The placenta is fully formed and functioning from 10 weeks gestation. At this point and up to 20 weeks gestation the placenta weighs more than the growing fetus as it is supporting early life and growth.
Fully formed, the placenta is a round disc shape, about 20cm in diameter and 2.5 cm thick at the centre. It weighs approx. 700gms. The placenta has two sides, one which attaches to the mothers uterine wall. This side is dark red in colour and is made up of many lobes, called cotyledons. These lobes adhere to the uterus and connect with a mothers’ circulation. The other side of the placenta, the fetal side, is shiny in appearance and is where the baby is connected by the umbilical cord to the placenta, within the placental sac.
The Fetal Sac & Umbilical Cord
The fetal sac is made up of a sturdy double membrane which holds the baby and the amniotic fluid. The amniotic fluid maintains temperature, equalizes pressure and protects the fetus from injury.
The umbilical cord connects the fetus to the placenta. The cord is approximately 50 centimeters in length, and contains two arteries and one vein, which are protected and enclosed by Wharton’s Jelly. The jelly allows the cord to remain soft and flexible. The umbilical vein delivers oxygen and nutrient rich blood to the fetus while the artery returns blood back to the mothers’ blood stream. The umbilical cord plays a vital role in managing respiration, nutrition, storage, excretion and protection of the fetus whilst in utero. The placenta can also excrete hormones, one being Human Chorionic Gonadotrophin ( hCG ) which is found in large supply in early pregnancy and is often tested via a blood test or urine to confirm a pregnancy. This is also the hormone which gives us many of the early pregnancy symptoms.
To help the fetus develop and grow the placenta, with all of its parts, works hard to carry out functions that the fetus is unable to do for itself over the pregnancy period.
Pregnancy ultrasound examinations include checking the placenta for its efficiency and function, to make sure your baby is growing well. The location of the placenta within the uterus, is one purpose of the 18-20 week scan.
If you have any questions relating to this information, please don’t hesitate to contact us, or discuss it at your next appointment.
Next months newsletter will continue with the Placenta particularly focusing on the third stage of labour (which is the delivery of the placenta) delayed cord clamping, cord blood banking, taking your placenta home and placental encapsulation.
By Penny Stanbury
Midwife at Dr Morris | Sydney Mother & Baby