From the Guidelines
The placenta is a vital organ that plays a crucial role in supporting the growing fetus by facilitating nutrient and oxygen transfer, removing waste products, and producing essential hormones. The placenta serves as the interface between maternal and fetal circulation, performing several critical functions. Its primary role is to facilitate the transfer of nutrients and oxygen from the mother's bloodstream to the fetus while removing waste products from the fetal circulation, as noted in studies on fetal growth restriction 1. It acts as a selective barrier, allowing beneficial substances like glucose, amino acids, fatty acids, vitamins, and minerals to pass through while blocking many harmful substances. The placenta produces essential hormones including human chorionic gonadotropin (hCG), estrogen, progesterone, and human placental lactogen that maintain pregnancy, support fetal development, and prepare the mother's body for childbirth and lactation, as discussed in the context of hypertensive disorders of pregnancy 1. It also provides immunological protection to the fetus by transferring maternal antibodies while preventing direct contact between maternal and fetal blood to avoid immune rejection. Additionally, the placenta serves as a temporary endocrine organ, regulating maternal metabolism and physiological adaptations to pregnancy, and its functions can be affected in conditions such as gestational diabetes mellitus 1. Key functions of the placenta include:
- Facilitating nutrient and oxygen transfer from the mother to the fetus
- Removing waste products from the fetal circulation
- Producing essential hormones to maintain pregnancy and support fetal development
- Providing immunological protection to the fetus
- Regulating maternal metabolism and physiological adaptations to pregnancy
- Storing iron for the fetus during the third trimester to support the baby's needs after birth. Overall, the placenta plays a vital role in ensuring the health and well-being of the fetus during pregnancy, and its functions are critical for a successful pregnancy outcome, as emphasized by the importance of placental function in preventing fetal growth restriction 1.
From the Research
Functions of the Placenta
The placenta plays a critical role in the health and wellbeing of both the fetus and its mother. Some of the key functions of the placenta include:
- Facilitating the delivery of oxygen and nutrients to the fetus 2, 3
- Removing waste products from the fetus 2
- Regulating the transport of nutrients to the fetus 4
- Producing hormones that facilitate fetal growth and development 2
- Acting as a gatekeeper between the mother and the fetus, adapting to variable nutrient supplies and alterations in maternal physiology and blood flow 4
Nutrient Transport
The placenta transports nutrients to the fetus through two main processes:
- Histiotrophic nutrition, where the fetus is nourished by uterine gland secretions in the first trimester of pregnancy 4
- Haemotrophic nutrition, where nutrients are delivered to the placenta via maternal blood in the second trimester of pregnancy 4
Placental Development
The placenta undergoes significant development throughout gestation, with different cell types and structures forming at various stages 3. Abnormal placental development can lead to pregnancy complications, such as fetal growth restriction (FGR) 5.
Placental Dysfunction
Dysfunctional placental development can lead to a range of pregnancy complications, including: