Placenta’s are like snow flakes – each one completely unique! I’ve heard so many stories of women not even seeing their placenta after birth. All the attention is on their new baby (and rightly so!) but it can be amazing to have a glance at your baby’s ‘first room mate’. Each time I hold a placenta in my hands I am in awe at the incredible organ that the mother grew to nourish her baby.
Normally a human placenta is round like a plate, with a diameter of about 22cm and is about 2-2.5cm thick. It can weigh about 500 grams (and is usually heavier with bigger babies). It has two very distinct sides. The maternal side (the side attached to the mother’s uterus) is usually deep red/maroon and is made up of lobes (called cotyledons). The fetal side looks like a tree with veins and arteries running over the surface. The umbilical cord is usually 50-60cm long and has two arteries and a vein. It normally inserts into the middle of the placenta. Just like each baby is unique, each placenta has it’s own characteristics, and some have variations listed below.
Velamentous Insertion: This is when some of the umbilical vessels run through the membranes (rather than attaching directly into the placenta). Although most babies are born fine, this kind of placenta does come with more risks. Because the vessels are unprotected, if the membranes (the bag of waters) is broken, it can puncture the vessels and cause hemorrhaging. Luckily, all the placenta’s that I have seen with this variation have all had happy endings.
Succenturiate Lobe: This is an extra lobe that is embedded in the membranes and connected to the main disc of the placenta via arteries/veins. According to radiopaedia.org this occurs in around 2/1000 pregnancies. It’s not really known what causes these accessory lobes. One theory put forth by babyworld.co.uk is that a slight irregularity or tiny scar on the uterine wall makes a small area inhospitable to the growing placenta, forcing a lobe to ‘move over’ and grow elsewhere. Some lobes are attached directly to the placenta via a ‘parenchymal bridge’, this is called a digitate lobe.
Circumvallate: This is when the fetal membranes create an edge of double folded membranes. It creates a thickened ring that makes a smaller circle (inwards from the edge of the placenta). The exact cause is unknown but midwife Patricia Edmonds says it can be caused by abnormal implantation of the placenta and the placenta and uterine wall growing at different rates.
Circummarginate: On this placenta, the point where the membranes attach is inside the edge of the placenta. The margin is thin and flat (whereas the circumvallate placenta has a thick ridge).
Bi-lobed: This is when the placenta has two near equal-sized lobes. It may form if the uterus is an unusual shape. It can also be caused by one part of the placenta implanting in the front of the uterus and another part of the placenta attaching to the back of the uterus. It is NOT caused by a twin pregnancy (even though this is a common myth). According to radiopaedia.org it is estimated to occur in around 4% of pregnancies.
Battledore/Marginal Insertion: This is when the umbilical cord inserts into the rim of the placenta (rather than in the middle). It is called ‘battledore’ because the placenta looks like a racket used in the game battledore (similar to badminton). If the umbilical cord inserts not quite centrally and not quite on the margin, it is called an eccentric insertion.
So, next time you have the chance to look at a placenta (maybe your own!), ask your midwife to explain all the different parts and see if you can pick any variations. If you aren’t really up for looking at it straight after birth, get someone to take photos so you can look when you’re ready. I’ve had clients not want to look after birth, but become curious later, and are glad to have photos! If you’ve already birthed, do you remember what your placenta looked like?