Journal of Clinical Neonatology

ORIGINAL ARTICLE
Year
: 2015  |  Volume : 4  |  Issue : 4  |  Page : 256--259

Influences of birth weight, gender, and pregnancy induced hypertension on cord blood leptin in growth restricted and normal neonates


Thomas Mathen Maveli1, Seema Pavaman Sindgikar1, Rathika Damodar Shenoy1, Puttige Kathyayani2, Sukanya Shetty2,  
1 Department of Pediatrics, K. S. Hegde Medical Academy, NITTE University, Mangalore, Karnataka, India
2 Department of Biochemistry, K. S. Hegde Medical Academy, NITTE University, Mangalore, Karnataka, India

Correspondence Address:
Rathika Damodar Shenoy
Department of Pediatrics, K. S. Hegde Medical Academy, NITTE University, Derlakatte, Mangalore - 575  018, Karnataka
India

Abstract

Leptin synthesized by adipose tissue has significant association with birth weight, body mass index and insulin-glucose ratio. Fetuses with growth restriction (FGR) have substantial reduction in adipose tissue; hence lower levels of leptin in cord blood. Hyperleptinemia has been observed in pregnancy induced hypertension (PIH). Objectives: To estimate leptin levels in cord blood of growth restricted and normal neonates and study the factors influencing the same. Methods: In this prospective study, a sample size of 40 each of growth restricted and appropriate for gestational age neonates were included. Data included maternal illnesses, anthropometry, maturity and ponderal index (PI). Cord leptin assay was done using commercial solid phase competitive ELISA and was expressed in ng/ml. Statistical analysis was done using t test and Pearson correlation co-efficient using recommended software. Results: Maternal PIH was the major etiological factor contributing to FGR (12, 30%, P =0.000). Mean cord leptin in ng/ml was 2.80±0.4 in growth restricted group and 3.53±0.5 in normal neonates with P value of 0.074. There was no correlation between cord leptin and birth weight (r=0.08; p=0.61) and PI (r=0.03; p=0.89). In female neonates and those born to mothers with PIH, mean leptin levels were 3.16±0.6 and 3.13±0.7 ng/ml respectively, higher in comparison with males and those born to mothers without hypertension. Conclusion: Mean cord leptin levels were lower in the growth restricted and higher in female gender and those born to maternal PIH. Cord leptin may be influenced by various maternal and fetal factors.



How to cite this article:
Maveli TM, Sindgikar SP, Shenoy RD, Kathyayani P, Shetty S. Influences of birth weight, gender, and pregnancy induced hypertension on cord blood leptin in growth restricted and normal neonates.J Clin Neonatol 2015;4:256-259


How to cite this URL:
Maveli TM, Sindgikar SP, Shenoy RD, Kathyayani P, Shetty S. Influences of birth weight, gender, and pregnancy induced hypertension on cord blood leptin in growth restricted and normal neonates. J Clin Neonatol [serial online] 2015 [cited 2020 Apr 6 ];4:256-259
Available from: http://www.jcnonweb.com/text.asp?2015/4/4/256/165690


Full Text

 Introduction



Leptin a product of the obese gene is a 16-kD plasma protein synthesized by adipose tissue normally. The rate of leptin production is directly related to adiposity and afferent signals from peripheral adipose tissue to hypothalamus stimulate energy expenditure and suppress appetite. Thus, leptin plays a key role in the regulation of adiposity, body weight, and energy balance.[1],[2] Studies in term infants indicate significant association of leptin with birth weight, body mass index, and insulin with the insulin-glucose ratio, leading to the conclusion that adipoinsular pathway is already active during the fetal and neonatal period.[3] The fetal-programing paradigm has generated much interest ever since Barker et al., postulated the relationship between fetal growth restriction (FGR) and later manifestation of diseases such as diabetes mellitus, hypertension, and coronary heart disease in adulthood. Alterations in leptin level in utero prompt substantive hypothalamic changes in fetuses that eventually result in the altered nutritional intake, energy metabolism, and adiposity later as children and adults.[4],[5]

Prenatal growth and gestational age (GA) play crucial roles in adipose tissue maturation and accumulation, modifying leptin and adiponectin secretions, endocrine, and metabolic functions.[6] The third trimester of gestation is of considerable importance for the fetal development of adipose tissue and growth with an exponential accumulation of fat mass. However, this is dramatically reduced in fetuses and newborns with growth restriction. At birth, body fat mass is <3% of total weight in newborns with FGR as compared to 15% in those with normal growth.[7],[8] Umbilical cord blood concentrations of leptin are shown to correlate with neonates' birth weight, and the inadequately developed fat tissue in preterm and FGR neonates leads to lower fetal leptin.[9],[10] Similarly, studies show maternal hyperleptinemia in pregnancy induced hypertension (PIH) and sexual dimorphism.[9],[11],[12],[13],[14] This study is designed to estimate the cord leptin concentrations in growth restricted and neonates with normal growth and the influence of birth weight, gender and maternal PIH and anemia on leptin levels.

 Methods



This study was designed to be prospective over a calendar year in the neonatal unit of a teaching hospital with a sample size of 40 each of growth restricted and appropriate for GA neonates. Institutional Ethical Committee clearance and an individual informed consent were obtained. FGR was diagnosed when two serial antenatal ultra-sonograms showed fetal growth percentiles <10th centile for GA based on fetal biometry. Term and late preterm (34–36 weeks) neonates with FGR were included. Unbooked pregnancy, prematurity <34 weeks, infant of diabetic mothers, severe birth asphyxia, major congenital malformations, and identifiable syndromes were excluded. The two groups were matched for maternal age, parity, and socioeconomic class.

The maternal data included information on maternal nutrition, pregnancy specific illnesses including anemia, infection, and PIH which could influence the fetal growth. The ultra-sonogram records were analyzed for fetal biometry and umbilical artery blood flow indices. Neonatal data at delivery included Apgar scoring, maturity, and growth parameters. Birth weights were recorded to the nearest 0.001 kg in calibrated electronic weighing scale, length in cm in an infantometer, and head circumference (HC) in cm with a nonstretchable measuring tape. All neonates with FGR were classified into symmetric and asymmetric based on ponderal index (PI). At the time of delivery, 3 ml of cord blood was collected and centrifuged and stored at −20° centigrade. Leptin assay was done by commercial solid phase competitive ELISA according to manufacturer's instructions. Leptin concentrations were expressed in ng/ml.

Statistical analysis were performed using software packages Statistical package for social studies (SPSS) version 16.0. The relationship in serum leptin concentrations between the growth restricted and normal groups was calculated by independent sample t-test. Values are expressed as 95% confidence interval derived from the standard error of the mean. A P < 0.05 has been considered significant. Similar statistical significances were also derived for gender and pregnancy related issues after merging the two groups. Leptin concentration was also correlated against the birth weight and PI in the growth restricted using Pearson correlation co-efficient.

 Results



Maternal and neonatal demography is given in [Table 1]. The mean maternal age was 26.683 ± 0.5 years and the majority were primigravidae (48.60%). Maternal PIH was the major etiological factor contributing to FGR in our study (12.30%, P = 0.000). The proportion of maternal anemia was comparable in both groups (P = 0.61), but mean maternal hemoglobin was lower in the FGR group (10.73 ± 0.2 vs. 11.04 ± 0.3) with statistical significance (P = 0.046). In addition to FGR, oligohydramnios was seen in five, and abnormal Doppler in the form of absent or reversal of umbilical blood flow was seen in two of the antenatal ultra-sonograms. In the growth restricted group, 16 (40%) were born preterm. The mean birth weights were 2055 ± 53.7 and 3055 ± 61.3 g in the two groups with no statistical significance. However, the other anthropometry data including length, HC, and PI were statistically significant between the two groups.{Table 1}

The comparison of levels against the growth restriction, gender, and maternal complications is given in [Table 2]. The mean cord leptin in ng/ml was lower in the growth restricted group (2.80 ± 0.4) in comparison with neonates who had appropriate growth (3.53 ± 0.5). The correlations between cord blood leptin and birth weight and PI in the growth restricted neonates are given in [Figure 1] and [Figure 2]. There was no correlation between cord blood leptin and birth weight (r = 0.08; P = 0.61) or PI (r = 0.03; P = 0.89). Though not statistically significant, higher levels of leptin were seen with female neonates and those born to mothers with PIH. Leptin levels were comparable in late preterm and term babies.{Table 2}{Figure 1}{Figure 2}

 Discussion



Leptin in pregnancy facilitates implantation, placental endocrine function, and fetal development is produced by maternal and fetal adipose tissues and placental trophoblasts.[12],[15] During pregnancy, maternal serum leptin level peaks in the second trimester until delivery when it declines rapidly. Umbilical venous blood leptin levels largely reflect fetal plasma leptin which is independent of placental leptin production. About 95% of placental leptin is released into maternal circulation with a minor contribution to fetal levels.[10],[16] There is a decline in the level in the newborn as well after birth which stimulates the feeding behavior.

Studies show the possible role of leptin on pregnancy related issues including PIH, birth weight, and FGR. In our study, though none of the relations were statistically significant several observations were made suggesting that leptin levels may be influenced by pregnancy related issues. Maternal anemia and maturity did not contribute to changes in fetal leptin levels. Maternal hyperleptinemia in PIH is placental in origin and is attributed to relative placental hypoxia and peripheral insulin resistance. This provides increased maternal free fatty acids and glucose for the fetus.[10],[12] The elevated fetal leptin seen in those born to mothers with PIH may be due to increased contribution from the placenta. Sexual dimorphism with higher leptin levels in female gender have been demonstrated by several authors.[9],[11],[13] This has been attributed to gender parse than a difference in fat distribution.[9]

The lower mean cord leptin levels in growth restricted neonates noted in our study though not statistically significant was similar to several others.[6],[9] In the largest study by Weyermann et al., the mean cord leptin in small (n = 103) and appropriate for GA neonates (n = 568) were 6.3 and 11.6 ng/ml, respectively, with a very high statistical significance. Their study also showed a significant correlation between cord leptin and birth weight. The mean cord leptin in Jaquet et al., study were 2.3 and 5.7 ng/ml in growth restricted and normal neonates with statistical significance. In the only published Indian study on cord leptin, Yajnik et al., noted the mean levels of 6.2 in 94 Pune born ethnic and 6.4 ng/ml in 60 London born Caucasian neonates with no statistical significance. Their mean birth weights were 2805 and 3475 g, respectively.[11] However, when matched for birth weight, cord leptin levels were significantly higher in the Indian babies suggesting a higher fat percentage. The lower level noted in growth restricted neonates reflects the relative body fat accumulation and may also play a role in catch-up growth until 24 months of age.

 Conclusion



Various factors including maternal illnesses such as PIH, the gender of the baby, and FGR may influence leptin levels and therefore, the statistical significance of studies based on the cord leptin. Longitudinal studies of various specific cohorts of newborn may be important to understand the role of leptin in growth and insulin resistance.

Indian Council of Medical Research, Government of India funded postgraduate dissertation project.

Financial support and sponsorship

Indian Council of Medical Research, Government of India funded postgraduate dissertation project.

Conflicts of interest

There are no conflicts of interest.

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