Placental insufficiency (or uteroplacental vascular insufficiency) is a complication of pregnancy when the placenta is unable to deliver an adequate supply of nutrients and oxygen to the fetus, and thus cannot fully support the developing baby. Placental insufficiency occurs when the placenta does not develop properly or because it has been damaged.
Placental insufficiency is commonly defined as a reduction in the maternal blood supply (reduced uterine artery blood flow). However, we define placental insufficiency to include reduction in maternal blood supply AND/OR the failure of the maternal blood supply to increase or adapt by mid-pregnancy.
These conditions can pose a significant risk to the mother and to the fetus.
The management of placental insufficiency is dependent upon additional tests and the unique characteristics of each patient. These include the medical history, previous pregnancy complications, healthy weight (BMI), blood pressure and ethnicity.
Findings of Placental Insufficency on Placental Function Testing
© Leslie Proctor, 2009
Once placental insufficiency has been diagnosed, the next steps depend on when in pregnancy the diagnosis is made.
Before the developing baby is viable (<24 weeks):
By offering women a program of serial testing at 12, 16 and 20 weeks, the diagnosis of placental insufficiency is typically made before any ill-effects on the mother (pre-eclampsia) or the developing baby (IUGR) are evident. Rarely, one or both may be seen before 20 weeks', and if so, the outcome is often unfortunately poor. However, most women and their developing babies with multiple test abnormalities before 24 weeks' are healthy at that point, although they do, as a pair, have a high chance of requiring delivery of the baby before 32 weeks (more than 30% chance).
The management approach of these patients is therefore is as follows:
Provide co-care with the referring obstetrician/family doctor/midwife, or assume full care if requested. Since the risk of preterm delivery is high, maintaining an ongoing relationship with the regional high-risk pregnancy unit is essential, since it permits a smooth transfer of care as needed.
Educate the woman about pre-eclampsia so she can self-monitor at home - this avoids late diagnosis when severe uncontrolled hypertension may result in earlier delivery (than if the blood pressure was found early and treated carefully) and can sometimes cause injury to the mother, or her developing baby.
Provide a plan of fetal monitoring using ultrasound, so that IUGR is recognized and monitored carefully.
Integrate this plan with regular visits (standard antenatal care)
After the developing baby is viable (>24 weeks)
If placental insufficiency is diagnosed in later stages of pregnancy, the disease can either:
- Remain sub-clinical. This means that it is never expressed as IUGR and/or pre-eclampsia, or
- One of several issues develops:
- Excess maternal weight gain, leg swelling, headaches -- this is pre-eclampsia
- The mother's stomach measures small, the baby is not moving very well - this is IUGR
- The baby has not moved for two days and no fetal heart beat can be found in the Clinic using a Doptone - this is stillbirth
- Some vaginal bleeding and/or contractions develop - this is preterm labour with placental separation, or abruption.
- If a degree of either pre-eclampsia or IUGR develops, then visit frequency is increased from bi-weekly to every week, then to twice/week and ultimately hospital admission for daily monitoring.
- If a concern about the need for delivery arises before 32 weeks', then the mother will be offered a course (2 intra-muscular [thigh] injections) of steroids. These steroids dissolve across the placenta to strengthen the developing baby's lungs, helping it to be ready if an early delivery is indicated.
- If pre-eclampsia and/or IUGR are more severe and are likely to require delivery before 32 weeks', then a high-risk Obstetrician or Maternal-Fetal Medicine specialist takes over to provide intensive outpatient or inpatient care.