The effect of pre-eclamptic toxaemia on the exchange of sodium in the body and the transfer of sodium across the placenta, measured by Na24 tracer methods

Alterations of Placental Sodium in Preeclampsia: Trophoblast Responses

BACKGROUND

Evidence suggests that increasing salt intake in pregnancy lowers blood pressure, protecting against preeclampsia. We hypothesized that sodium (Na+) evokes beneficial placental signals that are disrupted in preeclampsia.

METHODS

Blood and urine were collected from nonpregnant women of reproductive age (n=26) and pregnant women with (n=50) and without (n=55) preeclampsia, along with placental biopsies. Human trophoblast cell lines and primary human trophoblasts were cultured with varying Na+ concentrations.

RESULTS

Women with preeclampsia had reduced placental and urinary Na+ concentrations, yet increased urinary angiotensinogen and reduced active renin, aldosterone concentrations, and osmotic response signal TonEBP (tonicity-responsive enhancer binding protein) expression. In trophoblast cell cultures, TonEBP was consistently increased upon augmented Na+ exposure. Mechanistically, inhibiting Na+/K+-ATPase or adding mannitol evoked the TonEBP response, whereas inhibition of cytoskeletal signaling abolished it.

CONCLUSIONS

Enhanced Na+ availability induced osmotic gradient-dependent cytoskeletal signals in trophoblasts, resulting in proangiogenic responses. As placental salt availability is compromised in preeclampsia, adverse systemic responses are thus conceivable.

Hypertension in pregnancy

The hypertensive diseases of pregnancy commonly refer to a group of disorders whose definitions have changed over time within and among professional organizations. Pre-eclampsia, either mild or severe, is managed best with a policy of delivery at or beyond 37 and 34 weeks' gestation, respectively. Similarly, chronic hypertension,gestational hypertension, and chronic hypertension with superimposed pre-eclampsia are conditions wherein it is difficult to justify expectant management beyond 37 weeks' gestation. The approach to management before these gestational ages is subject to interpretation of a limited body of literature.

Risk factors for birth asphyxia and brain damage in pregnancy and labour

In this review the patho-physiology and risk factors of birth asphyxia are discussed. Simple and appropriate, but scientifically sound, technology for the prevention of birth asphyxia is described. This can be used at home, in the community, in health sub-centres and health centres to identify and assess risk factors so that appropriate referral can be made. Based on experience in developing countries, actions which can be performed by the mother, relatives, neighbours, traditional birth attendants and nurses and midwives are described.