Abnormal placental villous maturity and dysregulated glucose metabolism: implications for stillbirth prevention

OBJECTIVES

In the UK one in 250 pregnancies end in stillbirth. Abnormal placental villous maturation, commonly associated with gestational diabetes, is a risk factor for stillbirth. Histopathology reports of placental distal villous immaturity (DVI) are reported disproportionately in placentas from otherwise unexplained stillbirths in women without formal diagnosis of diabetes but with either clinical characteristics or risk factors for diabetes. This study aims to establish maternal factors associated with DVI in relation to stillbirth.

METHODS

Placental histopathology reports were reviewed for all pregnant women delivering at University College London Hospital between July 2018 to March 2020. Maternal characteristics and birth outcomes of those with DVI were compared to those with other placental lesions or abnormal villous maturation.

RESULTS

Of the 752 placental histopathology reports reviewed, 11 (1.5%) were reported as diagnostic of DVI. Eighty cases were sampled for clinical record analysis. All women with DVI had normal PAPP-A (>0.4 MoM), normal uterine artery Doppler studies (UtA-PI) and were normotensive throughout pregnancy. Nearly one in five babies (2/11, 18.5%) with DVI were stillborn and 70% had at least one high glucose test result in pregnancy despite no formal diagnosis of diabetes.

CONCLUSIONS

These findings suggest that the mechanism underlying stillbirth in DVI likely relates to glucose dysmetabolism, not sufficient for diagnosis using current criteria for gestational diabetes, resulting in placental dysfunction that is not identifiable before the third trimester. Relying on conventional diabetes tests, foetal macrosomia or growth restriction, may not identify all pregnancies at risk of adverse outcomes from glucose dysmetabolism.

Maternal and foetal placental vascular malperfusion in pregnancies with anti-phospholipid antibodies

OBJECTIVE

The objective of the study was to evaluate the rates of pathological placental lesions among pregnant subjects positive for aPL antibodies.

METHODS

We performed a longitudinal case-control study including 27 subjects with primary APS, 51 with non-criteria APS, 24 with aPL antibodies associated with other well-known CTDs enrolled at the end of the first trimester of pregnancy and 107 healthy controls.

RESULTS

Compared with controls and after correction for multiple comparisons, primary, non-criteria APS and aPL associated to CTD, subjects had lower placental weight, volume and area. After penalized logistic regression analysis to correct for potential confounders, placental lesions suggesting severe maternal vascular malperfusion (MVM) were more common among primary [odds ratio (OR) 11.7 (95% CI 1.3, 108)] and non-criteria APS [OR 8.5 (95% CI 1.6, 45.9)] compared with controls. The risk of foetal vascular malperfusion (FVM) was higher in primary APS [OR 4.5 (95% CI 1.2, 16.4)], aPL associated with CTDs [OR 3.1 (95% CI 1.5, 6.7)] and non-criteria APS [OR 5.9 (95% CI 1.7, 20.1)] compared with controls. Among clinical and laboratory criteria of APS, first trimester aCL IgG >40 UI/ml [OR 4.4 (95% CI 1.3, 14.4)], LA positivity [OR 6.5 (95% CI 1.3, 33.3)] and a history of pre-eclampsia at <34 weeks [OR 32.4 (95% CI 6.5, 161)] were the best independent first trimester predictors of severe MVM [area under the curve 0.74 (95% CI 0.6, 0.87)].

CONCLUSION

Compared with healthy controls, pregnant subjects with aPL antibodies have an increased risk of placental lesions, suggesting MVM and FVM. First-trimester variables such as aCL IgG >40 UI/ml and a history of pre-eclampsia were significant predictors of both severe MVM and FVM.