A cross-sectional study was conducted in Department of Obstetrics and Gynaecology at RL Jalappa Hospital and Research Centre, Kolar, Karnataka, India, for a period of 20 months from October 2018 to July 2020. Normotensive and preeclampsia pregnant females attending Outpatient Department (OPD) in Department of Obstetrics and Gynaecology at RL Jalappa Hospital and Research Centre, Kolar, Karnataka, constituted the study population. Study was approved by Institutional human Ethics Committee (IEC) (No.SDUMC/KLR/IEC/149). Informed written consent was taken from all the participants and only those participants willing to sign the informed consent were included in the study.

Sample size calculation: The sample size was deduced based on the data as per study between normotensive pregnant women and preeclamptic women in the study [14]. A total of 132 patients were divided into 66 each in group A and B were recruited by convenient sampling.

Group A- Singleton pregnancy with hypertension developed after 20 weeks of pregnancy.

Group B- Singleton normotensive pregnant women.

Inclusion criteria:

Pregnant women between 18-40 years of age.

- Hypertension developed after 20 weeks of pregnancy (group A).

Healthy normotensive pregnant women of ≥20 weeks gestation with a live singleton foetus were eligible and approached for recruitment (group B).

Exclusion criteria: Patient with coagulation disorders like idiopathic thrombocytopenia, sickle cell disease, viral hepatitis, cholestatic jaundice, acute fatty liver, malaria, drug induced hepatitis, dengue chronic hypertension.

A detailed clinical history along with the antenatal examination was done. The BP recording was documented. Patient with hypertension repeat BP recording after four hours were documented. Urine was examined for protienuria. Complete blood count was sent for all the patients and WBC, PC, MPV, PDW were documented in all patients. Then a comparison was made between the platelet indices of Normotensive (NT) pregnant women and women with preeclampsia. An attempt was made to find out whether there was an association between platelet indices and the severity of preeclampsia. Foetal outcome and maternal outcome were considered as primary outcome variable. Age, gestational age, PC, MPV (fl), PDW (fl) and mode of delivery was considered as other study relevant variables.

Criteria for diagnosis of preeclampsia and NT pregnancy

Preeclampsia: Onset of a new episode of hypertension during pregnancy, characterised by:

This disorder can have an early onset (preeclampsia starting before 34 weeks of gestation) or late onset (after 34 weeks of gestation) and can be classified as mild or severe, depending on the severity of the symptoms present.

Mild preeclampsia: Systolic ≥140 mmHg or diastolic ≥90 mmHg, over 20 weeks of gestation (in a woman with previously normal blood pressure) and 24 hour urine collection protein ≥0.3 g (urine dipstick test ≥1+).

Severe preeclampsia: Systolic ≥160 mm Hg or diastolic ≥110 mmHg (on two occasions at least six hours apart; in a woman on bed rest) and 24 hour urine collection protein ≥5 g (urine dipstick test ≥3+; in two random urine samples collected at least four hours apart) [16].

Pregnancy Induced Hypertension (PIH) is defined as a Systolic Blood Pressure (SBP) reading of at least 140 mmHg and/or a DBP reading of at least 90 mmHg. According to the American College of Obstetrics and Gynaecology (ACOG), PIH is attributed to four main conditions, pre-existing chronic essential hypertension; gestational hypertension; preeclampsia; and chronic hypertension exacerbated by preeclampsia or gestational hypertension (ACOG Practice Bulletin., 2019). New-onset hypertension that appears after 20 weeks of gestation in two episodes at least four hours apart is mainly due to gestational hypertension or preeclampsia. If this elevation in blood pressure is coupled with evidence of systemic involvement, such as proteinuria, the patient is said to be preeclamptic [17].

Normotensive (NT): Pregnant women who had SBP readings below 140 mmHg and DBP readings below 90 mmHg were considered normotensive. Hypertensive: Hypertensive women (Group II) were diagnosed according to the American College of Cardiology (ACC) criteria, with SBP of at least 140 mmHg and/or DBP of at least 90 mmHg (ACC criteria, 2018) [17].

The normal values for MPV are 8.4-12.0 fl, PDW 8.0- 14.0 fl, normal PC 150,000-450,000 microlitre of blood [18].

The results were represented as Mean±SD (Standard Deviation), categorical variables were represented as percentages. For normally distributed quantitative parameters the mean values were compared between study groups using independent sample t-test (two groups). Categorical outcomes were compared between study groups using Chi-square test. The p-value <0.05 was considered significant statistically. Statistical analysis was done by using coGuide version V.1.0 was used for statistical analysis [19].

A total of 132 participants were included in the final analysis with 66 participants in each group A (preeclamptic) and Group B (normotensive). Out of 66 participants in group A, majority 43 (65.1%) were in between 21-30 years of age and 52 (78.7%) in group B were in between 18-25 years of age, as shown in [Table/Fig-1].

Comparison of platelet parameters across the groups: Mean and SD of platelet parameters of the groups are shown in [Table/Fig-2]. The average platelet parameters showed a significant difference among the categories of women. The mean PDW (fl) was 12.62±2.14 in group A and in group B it was 10.98±1.06. The mean MPV (fl) was 10.27±1.11 in group A and in group B 9.81±1.01. There was a statistically significant difference in clinical parameters like PC, PDW (fl) and MPV (fl) between the study groups (p-value <0.05).

Comparison of mode of delivery between groups: Out of 66 participants in group A, 43 (65.15%) preeclamptic cases had Lower Segment Caesarean Section (LSCS) whereas in group B, 40 (60.6%) healthy pregnant women had LSCS. Mode of delivery was not statistically significant among two groups as shown in [Table/Fig-3].

Comparison of foetal outcome between groups: In the present study, adverse foetal outcomes were more in group A than group B. In group A, 40 babies born to preeclamptic mothers showed adverse outcomes. Foetal parameters did not show any significance among groups [Table/Fig-4].

Comparison of maternal condition between groups: In group A, 39 cases and in group B, 26 cases showed abnormalities. There was no statistically significant difference noted in maternal conditions among groups as shown in [Table/Fig-5].

Comparison of baby outcomes between groups: Neonatal Intensive Care Unit (NICU) admission was reported more in preeclampsia group as 28 (42.42%) compare to normotensive group as 25 (37.88%) where as the baby outcomes shown statistically not significant difference between two study groups (p-value=0.239) as shown in [Table/Fig-6].

Comparison of indication for LSCS between groups: Among the preeclamptic women (Group A) in study population, indication for LSCS was previous LSCS for 6 (13.95%) participants, previous 2 LSCS for 2 (4.65%) participants, Foetal distress for 15 (34.88%) participants, Severe preeclampsia with uncontrolled BP readings for 4 (9.3%) participants, cephalopelvic disproportion for 3 (6.98%) participants, prolonged labour for 6 (13.95%) participants, placenta previa for 1 (2.33%) participants, malpresentation for 2 (4.65%) participants and maternal desire for 4 (9.3%) participants as shown in the [Table/Fig-7].

The distribution of BP in the preeclamptic patients has been shown in [Table/Fig-8].

India contributes to large number of maternal deaths occurring globally even with rapid economic progress in past two decades because of many factors like less female literacy rate and lesser access and use of reproductive health services [11]. The aim of this study was to compare PC, and platelet indices (MPV, PDW, between preeclamptic and normotensive pregnant women and assess their role in diagnosis and prediction of preeclampsia development. In the present study, adverse foetal outcomes were more in group A than group B. In group A, 40 babies born to preeclamptic mothers showed adverse outcomes. Twelve (30%) cases suffered IUGR. In group A, 39 cases and in group B, 26 cases showed maternal abnormalities and placental abruption and anaemia were the main abnormalities observed in both the groups.

The majority of the subjects were in the age group of 21-30 years in group A and 18-25 years in group B the present study. This finding was in comparison to a cross-sectional study by Gogoi P et al., where the mean age of the women with preeclampsia was 28.5±5.6 years compared with 27.8±5.5 years in the control group (p>0.05) [20]. In the present study majority 31 (47%) were primagravida in group A and 25 (38%) in group B. This finding was in contrary to a case-control study by Hassan HES et al., where 9 (22.5) out of 40 in group A (healthy patient) and 18 (40%) out of 45 in group B (preeclampsia) were primagravida [21]. Primiparous women have increased risk when compared with multiparous women because immune tolerance will be developed during first pregnancy which will be carried over to subsequent pregnancies. This is applicable only when the first pregnancy is free from preeclampsia. This finding was in similarity with a hospital based unmatched case control study by Grum T et al., where primigravida was found to be risk factor for preeclampsia on the multivariable analysis and the odds of developing preeclampsia were 2.68 times higher in women with primigravida comparing to the women with multigravida (AOR: 2.68 95% CI: 1.38, 5.22) [22].

This observation of low PC in women with preeclampsia was similar to that found in studies like study by Mohapatra S et al., Annam V et al., [23,24] The PCs were lower while the MPV, PDW and PLCR were increased in preeclampsia and eclampsia as compared to control group, Dogru HY et al., prenatal thrombocyte counts were separated into three groups as 150,000/mm³ (Group 3), mean thrombocyte volumes of groups were calculated 10.11±0.72 fl, 18±0.48 fl, 7.82±0.53 fl, respectively [25], Chirag Buch A et al., In severe grade, the mean PC was on lower side than mild to moderate grade [26], however, it was not statistically significant. Though, platelet indices like MPV, PDW and PLCR are on higher side in severe grade of preeclampsia as compared to mild to moderate grade, it was also statistically insignificant and Freitas LG, et al., PDW was higher in preeclampsia comparing to normotensive pregnant (p=0.028) and to non pregnant women (p<0.001) [27]. MPV was higher in sPE comparing to normotensive pregnant and non pregnant women (p=0.05 and p<0.001, respectively. The main reason for decrease in PC in preeclampsia is endothelial cell activation and dysfunction which causes increased consumption of platelets.

Platelet activation causes morphological changes of platelets. These changes include changes to spherical shape and pseudopodia formation. Platelets with increased number and size of pseudopodia differ in size thus increasing PDW. There was a significant difference statistically in clinical parameters like PC, PDW (fl) between the study groups in the current study. This finding of increased PDW in women having preeclampsia was reported in studies by Mohapatra S et al., (2.38 lacs/mm³±0.33 in control group, 2.23 lacs/mm³±0.19 in mild PIH, 1.82 lacs/mm³±0.45 in preeclampsia and 1.21 lacs/mm³±0.49 in eclampsia) [23], Chirag Buch A, et al., In severe grade, the mean PC was on lower side than mild to moderate grade, however, it was not statistically significant [26]. Though, platelet indices like MPV, PDW and PLCR are on higher side in severe grade of preeclampsia as compared to mild to moderate grade, it was also statistically insignificant and Freitas LG et al., platelet activation causes endothelial dysfunction and increased platelet consumption during low grade intravascular coagulation [27]. This results in release of younger platelets by bone marrow which increases MPV because of their larger size [28].

The increase in MPV associated with preeclampsia is reported in study by Chirag Buch A et al., and in another study by Gioia S et al., a study by Özdemirci Ş, et al., [26,29,30]. Another study Kanat-Pektas M et al., concluded that when MPV of 10.1 or more and PAPP-A MoM (pregnancy associated plasma protein) of 0.33 or less are conjoined as a threshold, the pregnancies can be prediced with high sensitivity and specificity that they are at risk of developing preeclampsia [31]. Another two studies by Yang SW et al., and Bellos I et al., also reported MPV as a good predictor for preeclampsia [32,33].

Out of 66 participants in group A, the mode of delivery was vaginal for 34.8% participants and LSCS for 65.1% participants. Out of 66 participants in group B, the mode of delivery was vaginal for 39.3% participants and LSCS for 60.6% participants. In a systematic review by Amorim MMR et al., through Cochrane database system concluded that there is no evidence from randomised controlled trials to inform decisions regarding planned caesarean section versus vaginal birth for severe preeclampsia [34].

On comparing the neonatal outcomes, it was found that IUGR was noted in 30% in preeclampsia group as against 23% in group B normal group. This finding was supported in a study by Odegard RA et al., which concluded that severe and early onset preeclampsia were associated with significant foetal growth restriction [35]. Foetal distress was also noted to be in a greater number of participants with preeclampsia.

There was not much difference in percentage of neonates shifted to NICU after birth in two groups in the study. Twenty eight (42.42%) in group A and 25 (37.88%) in group B were admitted to NICU.

The novelty in this study is the simultaneous use of a combination of PC and MCV and PWD as markers for prediction of preeclampsia. These simple and relatively inexpensive markers can be used for close prenatal monitoring, help earlier recognition of preeclampsia in high risk cases and thus allow appropriate anti-hypertensive therapy. Further insight into the pathophysiological role of platelets in preeclampsia may facilitate a targeted strategy for preeclampsia prevention.

The main limitation was small sample size and generalisation of results requires support of evidence from similar large studies.

This study concluded that there is decrease in PC and increase in the platelet indices like MPV, PDW in preeclampsia group compared to normotensive group and the difference in laboratory findings of platelet indices was significant among the groups. Platelet indices can be used as a prognostic tool, for prediction of preeclampsia and help in improving the feto-maternal outcome. Further multicenter studies with large numbers of patients and prolonged follow-up are required in this population to confirm these findings.