Twin pregnancies with ICP are more complicated than singletons; study explains why?

CHINA: A recent study published in the BMC Pregnancy and Childbirth has revealed that twin pregnancies with Intrahepatic cholestasis of pregnancy (ICP) were associated with a higher risk of cesarean section (CS), preterm birth (PTB), fetal distress, and neonatal intensive care unit admission as compared to singleton pregnancies which relate to higher Total Bile Acid levels (TBA), involved in uterus-placenta-fetal circulation. It can be transferred through the placenta.

The characteristic findings in ICP is maternal persistent pruritus, increased TBA concentrations and elevated serum liver aminotransferase activity, usually presented in the late second or third trimesters.

The prevalence range of ICP is wide, from 0.2 to 25%, but it is more prevalent in multiple pregnancies, nearly five times more than singleton pregnancies. In twin pregnancies, it is approximately 20-25% The complications of ICP include preterm birth (PTB), meconium-stained amniotic fluid (MSAF), fetal distress and hypoxia, intrauterine fetal death, respiratory distress syndrome (RDS), NICU, etc.

The complicated condition requires active management and close antenatal monitoring in pregnant women. The severity of ICP is more in twin pregnancies than in singletons, but there is a lack of data elucidating this.

Considering this, a retrospective cohort analysis was conducted by Chunyan Deng from the Department of Obstetrics and Gynecology of West China Second University Hospital for twin pregnancies with ICP. The duration of the study was five years.

The researchers were hopeful that their study would provide important insights and evidence for the treatment.

The key points of the study are:

• The study included 633 twin and 1267 singleton pregnancies (with ICP).
• A correlation study was analyzed on TBA levels from maternal serum, fetal umbilical venous blood, and amniotic fluid of twin pregnancies.
• On comparing twin pregnancies vs singleton, there was a higher risk in twin pregnancies.
• The findings for risk of CS, PTB, fetal distress and NICU were 96.4% vs 76.1%, 82.6% vs 19.7%, 2.0% vs 1.3% and 23.6% vs 5.1%, respectively.
• There were significant increasing TBA levels with P < 0.05.
• TBA ≥100 μmol/L was reported in twin pregnancies.
• CS, Preterm Birth, fetal distress, neonatal asphyxia, and meconium-stained amniotic fluid incidence in percentage were recorded as 94.4, 100, 11.1, 5.6, and 36.1%, respectively.
• A positive correlation was recorded between the maximum maternal TBA levels and TBA levels in the amniotic fluid and umbilical cord blood. The P value was  < 0.05.
• There was a positive correlation in TBA levels in umbilical cord blood and amniotic fluid, which was significant with r = 0.52 and P < 0.05.

The researchers explained that in ICP, stillbirth is the most lethal complication, higher when TBA ≥ 100 μmol/L. Stillbirth is prevalent in 3.9% of twin pregnancies with ICP, as said by Liu et al.

The co-researcher added that in our study, we reported the rate of stillbirth in twin pregnancies with ICP as 0.4%. Our strategies may be implemented to prevent stillbirth.

We discovered that the rate of stillbirth and PTB was 0.4% and 82.6 % in twin pregnancies with ICP.

Our findings suggest that peak TBA levels fluctuate throughout pregnancy, which may rise rapidly near term even with medications, so it is essential to closely monitor TBA levels.

We suggest that once ICP is diagnosed, it is important to repeat the TBA test until delivery. This aid in guiding the perinatal management of ICP. This is very useful in severe cases. They added.

In ICP, UDCA lower serum TBA levels and also improve liver function. In our study, UCDA treatment was provided to participants. Our study has discovered that high TBA levels revert to normalcy almost 1 to 5 weeks after birth. The function of the liver returned to normal at 4 to 6 weeks in our study.

We hypothesized that TBA is transported through the placenta and has involvement in uteroplacental-fetal circulation.

We are the first to investigate the existing link between maternal serum, amniotic fluid and umbilical cord blood. Finally, we are the first who investigates the link between maternal serum TBA levels and umbilical cord blood electrolyte and bilirubin levels.

The findings of our study give new directions for research and a better understanding of the etiological mechanisms of bile salt and electrolyte transport pathways in ICP.

Further reading:

Xu, T., Deng, C., Zhan, Y. et al. Perinatal outcomes associated with ICP in twin pregnancies were worse than singletons: an almost 5-year retrospective cohort study. BMC Pregnancy Childbirth 22, 820 (2022). https://doi.org/10.1186/s12884-022-05160-6