Are pregnancies with a fetus diagnosed with hydrops fetalis at increased risk of developing preeclampsia?

Hydropic Fetuses and Preeclampsia Risk

Yes, pregnancies with hydrops fetalis are at significantly increased risk of developing preeclampsia, specifically severe preeclampsia, with an approximately 3-fold increased risk compared to the general population. 1

Magnitude of Risk

The association between fetal hydrops and preeclampsia is well-established and clinically significant:

• Severe preeclampsia occurs in 5.26% of pregnancies with hydrops fetalis compared to 0.91% in the general population (p < .001), representing a statistically significant 5-fold crude increase 2
• After adjusting for confounders including fetal anomalies, polyhydramnios, race/ethnicity, nulliparity, chronic hypertension, and diabetes, hydrops remains an independent risk factor with an adjusted odds ratio of 3.13 (95% CI 1.91-5.14) 2
• Mild preeclampsia rates are not significantly elevated (2.86% versus 2.02%, p = .29), indicating the risk is specifically for severe disease 2

Mirror Syndrome: The Most Severe Manifestation

Mirror syndrome represents the most critical maternal complication, occurring when the mother develops edema that "mirrors" the hydropic fetus, and is considered a form of severe preeclampsia. 1

Clinical Features of Mirror Syndrome

• Edema occurs in approximately 90% of cases 1
• Hypertension develops in 60% of cases 1
• Proteinuria is present in 40% of cases 1
• Additional manifestations include headache, visual disturbances, oliguria, elevated uric acid, abnormal liver function tests, elevated creatinine, thrombocytopenia, anemia, and hemodilution 1
• Pulmonary edema represents the major maternal morbidity, occurring in 21% of mirror syndrome cases 1

Pathophysiology

The same imbalance of angiogenic and anti-angiogenic factors (elevated sFlt-1 and soluble endoglin) described in severe preeclampsia has been observed in mirror syndrome cases, with correction following treatment and resolution of the hydrops. 1

Clinical Management Implications

Surveillance Requirements

Heightened surveillance for signs and symptoms of severe preeclampsia is warranted in all pregnancies complicated by fetal hydrops. 2

• Serial maternal blood pressure monitoring throughout pregnancy is essential 3
• Monitor for symptoms of severe preeclampsia: right upper quadrant/epigastric pain, headache, visual disturbances, and edema 1
• Laboratory monitoring should include assessment for thrombocytopenia, elevated liver enzymes, and renal function 1

Treatment Considerations for Treatable Hydrops

In cases with treatable etiologies of hydrops (fetal arrhythmia, hydrothorax, parvovirus, bladder obstruction), successful treatment of the hydrops can lead to resolution of both the fetal condition and maternal mirror syndrome. 1

Delivery Indications

For most cases of nonimmune hydrops fetalis, including all cases without a treatable etiology, development of mirror syndrome necessitates delivery. 1

• Given the risks of expectant management of severe preeclampsia, this approach should be taken only with caution 1
• Delivery should not be delayed if the maternal condition deteriorates 1
• Preterm delivery is recommended only for obstetric indications, including development of mirror syndrome 1

Additional Maternal Complications

Beyond preeclampsia, hydrops fetalis is associated with multiple serious maternal complications:

• Eclampsia 2
• Acute renal failure 2
• Pulmonary edema 2
• Postpartum hemorrhage 2
• Blood transfusion requirement 2
• Disseminated intravascular coagulopathy 4

Maternal complications occur in approximately 36-50% of pregnancies with fetal hydrops. 4, 5

Evidence from Twin Pregnancies

Case reports demonstrate that selective termination of a hydropic twin in dichorionic pregnancies can reverse maternal preeclamptic findings, providing strong evidence for the causal relationship between fetal hydrops and maternal preeclampsia. 6

Common Pitfalls to Avoid

• Do not assume mild preeclampsia risk is elevated—the increased risk is specifically for severe preeclampsia 2
• Do not delay delivery when mirror syndrome develops in non-treatable hydrops cases, as maternal deterioration can be rapid 1
• Do not underestimate the frequency of maternal complications—they occur in up to half of hydrops cases and require vigilant monitoring 4, 5
• Do not miss the opportunity to treat reversible causes of hydrops (arrhythmias, anemia, effusions), as successful fetal treatment can resolve maternal mirror syndrome 1