Is salivary uric acid, a putative biomarker of pre-eclampsia, of maternal, placental, or fetal origin?

OBJECTIVES: Increased salivary uric acid (sUA) represents a potential biomarker predictive of pre-eclampsia (PE), but its origin is unclear. The study explores whether sUA levels reflect maternal or feto-placental physiological stress and whether sUA levels in these cases correlate with amniotic fluid (fetal origin), maternal blood (maternal origin), or cord blood (fetal vs placental origin). STUDY DESIGN: Pregnant women (n = 39) undergoing amniotomy or caesarean section after 34 gestational weeks were designated into three groups of either maternal, feto-placental, or no signs of physiological stress: women (n = 15) in the established first phase of active labour and without any signs of fetal growth restriction (FGR) or PE were assigned to the maternal stress group, women (n = 6) with an ultrasound-based diagnosis of FGR, with or without PE, were assigned to the feto-placental stress group, and women (n = 18) not yet in active labour and without any signs of FGR or PE, were assigned to the control group. Uric acid levels in corresponding samples of amniotic fluid, saliva, maternal blood, and cord blood were compared between groups and between body compartments within each group. RESULTS: The feto-placental stress group showed increased UA levels in saliva (median, interquartile range [IQR]: 0.47 [0.38] mmol/L, P = 0.023) and maternal blood (0.42 [0.13] mmol/L, P = 0.032), but no differences in amniotic fluid or cord blood compared with the other groups. Within the control and maternal stress group, sUA levels were lower compared with maternal blood (0.20 [0.08] vs 0.25 [0.08] mmol/L, Pcontrol = 0.018; 0.20 [0.06] vs 0.26 [0.08] mmol/L, Pmaternal = 0.001) and highest in amniotic fluid (control group (0.49 [0.18] mmol/L): Pmaternal,blood = 0.001, Pumbilical,artery = <0.001, Pumbilical,vein = <0.001, Psaliva = <0.001) (maternal stress group (0.56 [0.23] mmol/L): Pmaternal,blood = 0.021, Pumbilical,artery = 0.006, Pumbilical,vein = 0.004, Psaliva = 0.003). Levels did not differ between compartments in the feto-placental stress group. CONCLUSIONS: Salivary and maternal blood UA levels were increased in the feto-placental stress group with salivary levels increasing more than blood levels compared with the maternal stress and control groups, whilst UA in amniotic fluid were not different between the groups, suggesting a placental origin and potential use of sUA as a biomarker of placental dysfunction, including FGR and severe PE.

Pregnant women's attitudes to and experiences with a smartphone-based self-test for prediction of pre-eclampsia: a qualitative descriptive study.

OBJECTIVES: To explore attitudes to and experiences using a smartphone-based self-test for prediction of pre-eclampsia among pregnant women. DESIGN: A qualitative, descriptive study. SETTING: An obstetrical care unit at a university hospital in Denmark. PARTICIPANTS: Twenty women who had participated in the Salurate trial, a clinical trial testing the efficacy of a smartphone-based self-test for prediction of pre-eclampsia, were purposefully chosen for the study, using maximum variation sampling. DATA COLLECTION AND ANALYSIS: Data were collected by semistructured, individual, face-to-face interviews conducted from 4 October 2018 to 8 November 2018. Data were transcribed verbatim and analysed by means of thematic analysis. RESULTS: Qualitative thematic analysis resulted in the identification of three main themes: Raising awareness, self-testing has the potential to be an integrated part of pregnancy and trusting in technology. Two subthemes were identified under each main theme. CONCLUSIONS: The smartphone-based self-test for prediction of pre-eclampsia has potential to be integrated into antenatal care, and women found it feasible to use. However, testing affected the participating women psychologically, leading to feelings of worry as well as safety. Therefore, if self-testing is implemented, it is important to take actions to handle adverse psychological side effects, including increasing knowledge on pre-eclampsia and having healthcare professionals ongoingly address the psychological state of women throughout pregnancy. In addition, it is essential to emphasise the importance of subjective bodily sensations during pregnancy, including fetal movements. Further studies on the experience of being labelled low risk versus high risk for pre-eclampsia are warranted since this was not investigated in this trial.

Salivary uric acid as a predictive test of preeclampsia, pregnancy-induced hypertension and preterm delivery: A pilot study.

INTRODUCTION: There remains a need for a non-invasive, low-cost and easily accessible way of identifying women at risk of developing hypertensive disorders in pregnancy. This study evaluated the predictive value of longitudinal salivary uric acid measurement. MATERIAL AND METHODS: Pregnant women (n = 137) from 20 weeks of gestation were recruited at St Richards Hospital, Chichester, UK, for this prospective cohort study. Weekly samples of salivary uric acid were analyzed until delivery. Information regarding pregnancy and labor were obtained from the patient's record after delivery. Independent t tests were used to compare mean levels of salivary uric acid in women with hypertensive complications and adverse fetal outcomes with women with normal pregnancies. Main outcome measures were preeclampsia, pregnancy-induced hypertension, spontaneous preterm delivery and small-for-gestational-age babies. RESULTS: From 21 weeks of gestation until delivery, levels of salivary uric acid increased significantly in women who subsequently developed preeclampsia and pregnancy-induced hypertension compared with women with normal pregnancies (preeclampsia-mean at gestational age 21-24, 95% confidence interval [95% CI] [mean GA21-24 ): 108 [63-185] vs 47 (39-55) µmol/L; P = .005; pregnancy-induced hypertension-mean GA21-24 : 118 [54-258] vs 47 [39-55] µmol/L; P = .004). In women who had spontaneous preterm delivery, salivary uric acid levels increased significantly from 29 to 32 weeks of gestation compared with women with normal pregnancies (mean GA29-32 : 112 (57-221) vs 59 (50-71) µmol/L; P = .04). In women who had babies small-for-gestational-age <10th percentile and small-for-gestational-age <3rd percentile, differences in salivary uric acid levels were insignificant. CONCLUSIONS: Elevated levels of salivary uric acid precede the onset of preeclampsia, pregnancy-induced hypertension and preterm delivery. Salivary uric acid may prove to be an early biomarker of hypertensive complications of pregnancy and spontaneous preterm delivery.