We have observed that newborns of the hypertensive mothers had lower median birth weight, lower median Apgar score and were delivered prematurely. A significant difference was also observed in the cord blood hematological parameters of newborns of mothers with HDP compared to normotensive mothers
Low birth weight and premature delivery
In the present study, newborns of hypertensive mothers had a significantly lower median birth weight compared to newborns of normotensive mother. The findings are consistent with those of previous studies whereby HDP’s was found to be a risk factor for LBW. This is due to utero-placental failure which consequently causes poor fetus nourishment in the womb (2,4).
Hypertensive disorder of pregnancy is a risk factor for indicated premature delivery. This explains the observed, low median gestation age at delivery in hypertensive mothers of our study. This is similar to findings from a study by Elgari et al (8) The positive association of LBW and premature delivery with neutropenia that was observed in this study is also consistent with other studies: which reported that neonatal stage of maturation and development, specifically VLBW is associated with neutropenia (9,10).
Poor neonatal granulocyte production as an outcome of maternal hypertensive disorder of pregnancy
In our study newborns of the hypertensive mothers had statistically and clinically significant lower median neutrophil count when compared to their normotensive counterpart. The prevalence of neutropenia was 50% and 9.8% in cord blood of newborns of hypertensive and normotensive mothers respectively. This is similar to other studies done in both Africa Asia and Europe (10–12). Among the neutropenic cases, more than half (55%) had severe neutropenia; Moreover, to the best of our knowledge the observed median neutrophil count in our HDP population is the lowest compared to those observed elsewhere. The reason as to why the neutrophil count is lowest in our population remains as the subject for future studies.
Neonatal neutropenia due to HDP can be self-limiting in less than 60 hours after birth; however, higher risk of nosocomial and other infections is also present in these newborns as neutropenia is known to independently predict sepsis. The risk is known to be there even after normal neutrophil levels has been attained (13). Neonatal neutropenia due to hypertensive disorders may be explained by several mechanisms such as:- a) Inhibition of fetal production of neutrophils by unidentified inhibitor which is present in cord blood serum of newborns of hypertensive mothers (9), b)Reduced numbers of circulating colony-forming unit-granulocyte macrophage (CFU-GM) and reduced neutrophil storage pools (14), c) Interaction of Fas to Fas ligand for apoptosis activation which cause the presence of raised Fas associated protein in the mother and infant. Fas associated proteins are associated with both chronic and congenital neutropenias (15,16), d) Shift into direction balance of erythropoiesis more than granulopoiesis due to placenta hypoxia which induce stem cell favoring the earlier and as a result dysgranulopoiesis's develops (17)
We found significantly low count in other granulocytes (basophil & eosinophil) and consequently leukopenias in cord blood of hypertensive mother’s newborns as compared to normotensive mother’s, These findings are similar to findings by Bolat et al (4). We anticipate that the above-mentioned mechanisms can also be used to explain the difference observed in these other granulocytes.
Neonatal thrombocytopenia due to hypertensive disorders of pregnancy
Newborns of hypertensive mothers had low median platelet count compared to newborns of normotensive mothers. Moreover, thrombocytopenia prevalence was 50% and 18.3% in newborns of hypertensive and normotensive mothers respectively. Similar findings have also been reported by other studies (2,4,18).
This is attributed to placental dysfunction and hypoxia which results in impairment of platelet production by several mechanisms such as a) Adherence of thrombocyte to the damaged endothelial region caused by segmental vasospasm and vasodilatation in the placenta of hypertensive mothers(19,20) b) Undefined factor which leads to DIC which is said to be transported to the baby by the placenta and cause thrombocytopenia in the newborn (19). (c) Depression of megakaryocyte proliferation due to placental hypoxia as a consequence of hypertension (21)