Overview

Placental insufficiency is a medical term used to describe poor placental function.¹ However, at present, there is no standardised definition for the condition. This point has been highlighted by various scientific articles. Thus, the term in clinical practice is a process of progressively deteriorating placental function. 

To understand the nature of the condition, and its implications on pregnancy, one must first understand the placenta and its functions.

In this article, we shall discuss the causes, risk factors, clinical features, evaluation and management of this condition. This work is meant to be informative only and is not meant to replace evaluation by a healthcare professional. It is important you see your physician for a diagnosis or treatment plan if you notice symptoms of placental insufficiency.

Importance of the placenta in pregnancy

The placenta is a specialised organ that develops during pregnancy and supports the growth and development of the fetus. The function of this organ is to exchange nutrients and waste products between the mother and foetus through their circulatory systems.

Nutrition and oxygen travels from the mother to the growing baby and carbon dioxide and waste products travel back to the maternal side for excretion. The placenta also secretes important hormones which affect pregnancy, metabolism of the baby, fetal growth, progress the pregnancy and later aid in the delivery of the baby, among others. 

Inefficiency of this placental unit, which may result in the foetus not receiving adequate nutrition or retaining waste products for longer, leads to “placental insufficiency”. This can cause significant problems in the pregnancy. Inadequate oxygen and nutrition causes the foetus’ system to attempt to conserve energy reserves and reduces the utilisation of these nutrients. This decreases foetal growth leading to a condition called Intra-Uterine Growth Restriction (IUGR).

Causes and risk factors

Factors contributing to placental insufficiency

At present, the exact causes and major reasons for placental insufficiency are not entirely understood. Studies are still going on to determine specific risk factors and their impact on the development and maintenance of the placenta.²

The known risk factors are as follows:³

• Maternal hypertension: This includes Pre-eclampsia, Gestational Hypertension or Chronic Hypertension. While the former two refer to an increase in blood pressure during pregnancy which resolves after the baby is born, the latter is a long-term condition that is not caused as a result of the pregnancy
• Maternal diabetes
• Maternal smoking: Cigarette smoking is known to lead to placental inadequacies
• Maternal drug use, such as heroin and cocaine
• Maternal alcohol consumption during pregnancy
• It is more common during the first pregnancy
• Older maternal age is known to be a risk factor as well
• Women with a previous history of an IUGR baby are more prone to a similar occurrence in subsequent pregnancies

Maternal conditions affecting placental function

Any health condition that a mother has tends to reflect in the growth of her baby during the intrauterine period. This may include:

• Malnutrition
• High Body Mass Index
• Certain medications like Anti-cancer medication, Anti-epileptics and Anticoagulants

Incidence and prevalence of placental insufficiency

Placental insufficiency is a potential cause of a number of complications in pregnancy including:

• Preterm labour– where a baby is born before attaining maturity
• Pre-eclampsia– increased Blood Pressure during pregnancy leading to protein in the urine
• Intra-uterine growth restriction
• Stillbirth

This is known to affect 10 to 15% of pregnancies. 

Prematurity is the leading cause of foetal death followed by intrauterine growth restriction (IUGR), which is a complication in nearly 4% to 6% of pregnancies.¹ In foetuses with Intrauterine growth restriction, the risk of spontaneous preterm labour is three times higher than those babies who have no growth restriction. There is also a five to six times higher risk of perinatal death in these cases. Unfortunately, almost 50% of newborns with IUGR are only detected after birth.

Signs and symptoms

A wide range of signs and symptoms are associated with placental insufficiency, but very few of these are specific to the condition. Thus, it can be difficult to diagnose on a purely clinical basis without tests. Some clinical signs include:

• Reduced fetal movement: This may be noticed by the mother as decrease in frequency of movements
• Poor growth of the baby: This may be noticed during routine antenatal checkups when measuring the tummy

Diagnosis of placental insufficiency

At present, due to the lack of a ‘standardised definition’ for Placental Insufficiency, the diagnostic criteria of the condition are difficult to define. However, techniques do exist to evaluate the functioning of the placenta during pregnancy and the blood flow through it.

The currently used methods for diagnosing placental inadequacy include:

Ultrasound and other imaging techniques

Ultrasonography (USG), also called an ultrasound, is a test where a small device called an ultrasound probe is used. This device gives off high-frequency sound waves which cannot be heard.

However, these waves bounce off different parts of the body when placed over the abdomen and these bounced waves are called “echoes”. The echoes are picked up by the probe and turned into a moving image on the screen. The doctor then evaluates the images to identify the structures underneath.

A special type of Ultrasound is the Doppler Ultrasound, which is now considered the best diagnostic method for placental insufficiency. The four forms of Doppler studies found to be useful are:

• Umbilical artery doppler – Which measures the flow of blood through the umbilical artery, the amount of resistance to this blood flow and the changes in the placenta as the pregnancy progresses. A higher resistance can indicate placental insufficiency
• Uterine artery doppler – This test measures the changes in blood flow through the uterine artery from before the pregnancy, to the changes occurring with the developing foetus
• Middle cerebral artery (MCA) doppler – This might be prescribed if the Umbilical Artery Doppler shows any abnormality. It tests the blood flow in the brain of the unborn baby
• Venous doppler – This can identify when the baby is experiencing any form of stress

Magnetic resonance imaging (MRI) 

This has been found to provide additional information to detect and diagnose placental insufficiency. It can detect any abnormality in the placenta, including any clots.

Complications of placental insufficiency

The possible effects of placental insufficiency on the developing foetus are complex and depend on many additional factors. However, the primary reason for these effects is the growing baby's lack of adequate oxygen and nutrition.

Inadequate nutrition can lead to the baby not being able to grow as expected. This is called Intra Uterine Growth Restriction (IUGR) and can cause the baby to have a low birth weight.⁵

Placental insufficiency also increases the chances of a premature birth. Babies born prematurely may have lungs that are not developed enough to breathe properly. Thus, your baby may have to stay at the hospital under care or observation for a longer period than most babies born at term.

The most serious complication is a complete absence of placenta formation which leads to a miscarriage. In the developing foetus, inadequate oxygen supply can lead to the blood flow being redistributed to the essential organs like the brain and heart. This means other organs such as the bowels and kidneys don’t receive adequate supply and may be underdeveloped.⁴

There is also a higher chance of intraventricular haemorrhage in newborns in this situation.

The foetus is also at risk for:

• Hypoglycaemia
• Hypoxic-ischaemic encephalopathy
• Low platelets (thrombocytopenia)
• Low white blood cells (leukopenia)
• Anaemia
• Cognitive defects as a child
• Chronic illnesses in adulthood

Management and prevention

Currently, there is no known treatment for placental insufficiency. The only possible management is to deliver the fetus if it is viable. However, some therapies known to improve placentation are Vitamin C and E¹, if there was any uncertainty about the placentation.

Close monitoring during pregnancy

People assigned female at birth (AFAB) with the following risk factors may be recommended a Doppler Ultrasound scan at 12 to 14 weeks gestation:

• Chronic hypertension
• Coagulation problems
• A history of Pre-eclampsia

In such cases, a low dose of Heparin may be prescribed.

Prevention strategies

While it is not possible to completely prevent Placental Insufficiency, certain measures can be taken to reduce the chances of it occurring, or diagnosing it early.

Prenatal care and regular check-ups

Being vigilant during the pregnancy, keeping track of foetal movements and looking out for any signs of abnormalities is important to identify placental insufficiency early.

If you notice a decrease in your baby’s movements, any bleeding from the vagina or feel pain, discomfort or any of the symptoms mentioned above in this article during your pregnancy, it is pertinent that you contact your healthcare provider.

It is also necessary to attend regular antenatal check-ups so the medical staff can monitor your pregnancy's healthy progression.

Healthy lifestyle choices during pregnancy

Maintaining a healthy diet and staying active can help ensure a healthy pregnancy and healthy baby. Maternal alcohol consumption, drug use, and smoking have all been linked to placental insufficiency, so it is important to avoid them.

Managing underlying health conditions

Since pre-existing health conditions like Diabetes Mellitus and Chronic Hypertension have been implicated in placental insufficiency, it is necessary to mention them to your healthcare provider during Antenatal check-ups and to take regular medications as prescribed.

Prognosis

A newborn who suffered from IUGR as a consequence of placental insufficiency and survived the early days of life would be at a higher risk of developing cognitive deficits in childhood, including cerebral palsy and seizure disorders compared to a baby with no growth restriction.

There is also evidence that suffering from IUGR as an infant predisposes an individual to chronic illness as an adult, including increased risk for developing coronary artery disease, hypertension, and diabetes.³

Summary

Placental insufficiency is a term that refers to the inability of the placenta to supply adequate nutrition and oxygen to a growing foetus during pregnancy. While there is no standardised definition, diagnostic protocol or treatment for this condition, there have been improvements in recent years.

The clinical presentation is usually in the form of decreased foetal movements, vaginal bleeding or in severe cases, miscarriage. Often the condition is diagnosed later, after the baby is born premature or with a low birth weight.

While it cannot be prevented, it is necessary to stay vigilant during your pregnancy, maintain a healthy diet, take medications as prescribed by a medical professional, and attend regular check-ups.