A prospective observational study was conducted for two years i.e., from November 2015 to November 2017 at Dr. TMA Pai hospital, Udupi, affiliated to Manipal Academy of Higher Education and approved by ethical committee of Manipal University, Manipal. The screening population consisted of 1500 women with singleton pregnancies who consented for first trimester aneuploidy screening at 11-13⁺⁶ weeks of gestation. Informed consent was taken from patients in Kannada and English languages about the study enrolment. Inclusion criteria were singleton pregnancies booked in the first trimester and consented for first trimester aneuploidy screening and willing to participate. Exclusion criteria were multiple pregnancies, chromosomal anomaly, lethal congenital anomaly, pre-gestational diabetes, chronic hypertension, chronic renal disorders, cardiac disorders and congenital viral infections.

Gestational age was based on last menstrual period with previous regular cycles and corresponding scan findings in first trimester ultrasound {Crown-Rump Length (CRL)} between 7-10 weeks of gestation. The disparity in CRL up to four days was considered acceptable. Patient’s age, height, weight, the presence of above mentioned medical illness, and other demographic characteristics were noted.

Three to four millilitres of venous blood sample was collected. The serum was separated and analysed at biochemistry laboratory of Kasturba Hospital, Manipal. The test was carried out by automatic analyser machine by Electrochemiluminiscence immunoassay (ECLIA) with Cobas e601 analyser. The results were calculated by Cobas e software and corrections were made according to weight, smoking and diabetes status. Measuring range for PAPP-A was 4-10,000 mIU/L. Appropriate dilution was carried out for PAPP-A of more than measuring range. The risk calculation was performed using software Sswd Lab version 5.0, and was given as MoM.

From the available cohort, 5^th and 95^th centile for PAPP-A values were obtained. All the women with PAPP-A of more than 95^th centiles were selected as cases and women with 5^th- 95^th centile serum PAPP-A were taken as controls. The foetal aneuploidy risk was calculated and risk of 1:250 or higher was taken as high risk for chromosomal abnormality for Down syndrome and risk of 1:100 was reported as screen positive for trisomy 18 and 16. Definitive testing was suggested for high risk of aneuploidy. The results suggestive of euploid were continued with respective groups. Women detected with major anomalies at second trimester scan were given option for termination of pregnancy. Pregnancy outcome information was obtained for Spontaneous Abortion (SA), Preterm Delivery (PTD), Large for Gestational Age (LGA), hypertension in pregnancy, gestational diabetes, oligohydramnios, Small for Gestational Age (SGA), mode of delivery and low birth weight baby.

LGA was defined as birth weight above the 90^th centile for the gestational age [4]. SA was determined as a loss of a pregnancy before 20 weeks of gestation [5]. PTD was defined as delivery before 37 completed weeks of gestation. Hypertension in pregnancy was determined as a blood pressure of more than 140/90 mm of Hg at least twice, after six hours of interval after 20 weeks of pregnancy with or without proteinuria. Isolated low liquor was defined as amniotic fluid of less than 7 cm after 28 weeks gestation in absence of any other foetal or maternal pathology for our study. Premature Rupture of Membrane (PROM) was defined as rupture of membranes after 37 weeks of gestation but before labour starts. SGA was defined as birth weight below the 10^th centile for the gestational age [6]. We used centile charts from Callen’s book of Ultrasound [7].

Statistical analysis was performed using Statistical Package for Social Science (SPSS) software version 16 and p-value <0.05 was considered statistically significant. Chi-square test was used to show differences between the study groups. The Student’s t-test was used for the comparison of means. Fisher’s-exact test was used when appropriate. Odds Ratio (OR) with 95% CI was calculated for certain outcomes.

Our cohort consisted of PAPP-A values between 0.50 and 8.6 MoM; range between 1079–113333 mIU/ml. Seventy patients (4.6%) with high PAPP A were found amongst screened 1500 pregnant women in the first trimester. The PAPP-A values of 0.49 and 3.10 Multiples of Median (MoM) were respective values for 5^th and 95^th centiles in our populations. The 1^st, 3^rd, 90^th and 99^th centile PAPP-A values were 0.324, 0.45, 2.4, 4.8 MoM respectively. PAPP-A value of >3.10 MoM were taken as cases and 200 women with normal PAPP-A (0.50 – 3.09 MoM) were considered as controls. We got 45 cases (64%) with values between 3.10-3.99 MoM, 17(24%) had 4-4.99 MoM and 8 (12%) had more than 5MoM. Our cohort had an age range of 18-38 years.

[Table/Fig-1] shows the group characteristics, where age, first trimester weight, BMI, CRL and β-hCG value of study and control group was comparable. The mean sampling period was 12.0 weeks in study group and 12.3 weeks in control group (p-value 0.001). The study group had 47(57%) nulliparous patient and control group had 129 (64.5%) nulliparous patients (p-value 0.86).

[Table/Fig-2] shows the incidence of pregnancy complications. There was no statistically significant difference in the incidence of threatened abortion and preterm delivery in both the groups. We found one major and minor malformations in the study group and three major and seven minor foetal anomalies in control group, here p-value-0.81, was insignificant. The minor soft markers were choroid plexus cyst [2], small atrial septal defect [2], perimembranous ventricular septal defect, polydactyly, single umbilical artery [2], hypospadias, renal pelvicalyceal dilatation etc. The incidence of hypertension in pregnancy and intrauterine growth restriction was lower in the study group, which was statistically insignificant. The incidence of diabetes and oligoamnios was almost same in both the groups. We did not find any case of late 1^st or 2^nd trimester abortion in any group. The incidence of PROM was lower in the study group than in the control group, which was statistically insignificant.

[Table/Fig-3] mentions the outcome of pregnancy in both the groups. Here we found mean gestational age at delivery was same. The mean birth weight was marginally different i.e., 3 kg and 2.9 kg in study group and control group. We found a low incidence of SGA and high incidence of LGA in the study group. However, statistically significant difference was found for SGA (birth weight <10%) only, OR-0.31 (95% CI – 0.11-0.85), suggested risk reduction of SGA with high PAPP-A. The difference in the incidence of LSCS and neonatal complications were not statistically significant between both groups. We had five cases of prolonged neonatal stay for respiratory distress syndrome [2], and hyperbilirubinemia in neonate [3].

The incidence of high PAPP-A in our study was 4.6%. it was noted high (7.9%) in the study by Timmerman E et al., [8]. For our study, 95^th mean centile value (SD) was 3.95±0.93 MoM, the same is mentioned as 3.9 MoM at 11 weeks of gestation [9]. In the FASTER trial, median 95% value achieved was 2.51 MoM [6].

The incidence of threatened abortion was almost same (11% vs 9%) in study and control group respectively, which is in agreement to worldwide incidence [10]. We did not have late 1^st trimester and early second trimester abortion. We had four major foetal anomalies, which were severe ventriculomegaly (hydrocephalus) with PAPP-A levels of 3.4 MoM in the study group and control group, three anomalies noted were (Double outlet right ventricle, vermian agenesis, and severe bladder outlet obstruction with hydronephrosis). All the four couple with major anomaly opted for termination of pregnancy, hence were not included in the study. Foetal severe ventriculomegaly has not been reported with high PAPP-A levels. Hence, it is incidental or associated with high PAPP-A could not be confirmed.

The incidence of hypertension in pregnancy and Intra-uterine growth restriction was less in the study group (4.2% vs. 10.5% in control group), which suggests the beneficial effect of high PAPP-A on effective placentation. The incidence of Diabetes in pregnancy was almost same in both the groups (8.5% and 7.5%), which was in agreement to the population incidence mentioned in various studies from South India (6.5 to 17%) [11]. The incidence of isolated low liquor is almost similar in both the groups (10% and 9.5%), shows higher PAPP-A doesn’t have influence on amniotic fluid levels. PROM was seen less in the study group (2.8%), while it was much higher (7.5%) in control group, which was statistically insignificant. This can be due to improved strength of membranes with higher PAPP-A. However, further studies are required to support the same. The incidence of PROM has been mentioned up to 10% [12], and our study has similar incidence in control group.

The mean gestational age was almost similar in both the groups, suggesting higher PAPP-A levels doesn’t affect the duration of pregnancy. The mean birth weight was higher in the study group. However, the difference was not statistically significant. We observed a linear correlation of birth weight with increasing PAPP-A levels, which was in agreement with the study by Habayeb O et al., [13]. Even SGA was seen in high PAPP-A group, but the incidence was low in the study group, and the difference was statistically significant (p-0.012). The trend of Large For Gestation (LGA) was observed with increasing PAPP-A levels [14].

The analytical method used was ECLIA, which is precise in measurement, recent and reliable method. Other modalities are time-resolved fluorescent assay using a Delfia analyser, a Kryptor analyser, and enzyme-linked immunosorbent assay on blood spot [15]. We believe that high PAPP-A means more cleavage of Insulin like Growth Factor Binding Protein (IGFBP), leading to high bio available IFG 1 and 2 levels, improving growth and metabolism, and better invasion of trophoblast to spiral arterioles. Hence, the possibility of macrosomia and less risk of hypertension in pregnancy and SGA.

The small sample size and non-randomized study pattern are limitations of the study. It represents south west coastal Karnataka population; the results cannot be implied to other parts of India. This is the first ever study from one of the highly populated country of the world, i.e. India and it confirms the findings of previous study. We recommend to look at PAPP-A MoM done at FTS for aneuploidy test as it may provide insight on recurrence of the complication in risk population and risk of certain events in low risk group.

PAPP-A assessment is a routine component of first trimester screening and as it provides information at no extra cost, it can be used to assess foetal well-being and pregnancy complications. Higher PAPP-A levels suggest the benign course of pregnancy. It can be an early manifestation of the healthy foetus in the absence of genetic abnormality. However, further studies are needed to prove its utility in hypertension in pregnancy.