alexa The Effect of Biological Factors on Birth Weight and Gestation in South Indian New-Borns

ISSN: 2472-100X

Journal of Pediatric Neurology and Medicine

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The Effect of Biological Factors on Birth Weight and Gestation in South Indian New-Borns

Grace Lalana Christopher*
Grace Specialist Clinic, India
*Corresponding Author: Grace Lalana Christopher, Grace Specialist Clinic, India, Tel: 91 99728229403, Email: [email protected]

Received Date: Apr 03, 2017 / Accepted Date: Apr 26, 2018 / Published Date: May 03, 2018

Abstract

Background: Understanding the effect of biological factors on birth weight of new-borns has public health importance because these indicators are associated with infant health and survival and influence development and health in later life.
Aim: The study was undertaken to determine the birth weight and gestational age characteristics in south Indian babies and correlated to biological factors. Settings and design: A retrospective study of consecutive singleton live births, who delivered in the hospital in a metropolitan city of Bangalore, South India.
Materials and Methods: A cohort of singleton live births, born from January 2015 to May 2017 were analysed to determine the mean birth weight and gestation and influence of various biological factors such as gender of baby, birth order, mother’s age, obstetric complication such as PIH and Diabetes etc.
Results: Among a total of 2789 singleton live births, the mean birth weight was 2873.73 ± 498.6 g, mean gestation was 38.2 ± 2 weeks and Low Birth Weight (LBW) <2500 g was 19.1%. The Term, male, later births, older mothers above 30 years and pregnancy of Pregnancy Induced Hypertension (PIH) and diabetes were associated with statistically significant higher birth weight P=0.001, P=0.002, P=0.0001, P=0.001, P=0.0006 and P=0.0001, respectively.
Conclusion: The mean birth weight and gestation for singleton live births in South India were determined, as well as the statistically significant impact of various biological criteria.

Keywords: Birth weight; Gestation; Biological factors

Aim

This is a retrospective study. The study was carried out with an aim of:

• Estimation of birth weight and gestational age of new-born confirmed by ultrasonogram undertaken within 18-20 weeks in singleton live term new-borns in order to obtain a standard birth weight and gestation reference range for Bangalore, South India

• Comparison of average birth weight of male and female babies

• Estimation of average birth weight in firstborn and that of later born babies

• Effect of other biological factors such as mother’s age and complications of pregnancy such as PIH and Diabetes on birth weight and gestation

• Comparison of the above mentioned statistics with available national and other regional studies.

Introduction

Birth weight is one of the most important factors that predict the survival, future development and growth pattern of a new-born baby [1-5]. Birth weight is mainly influenced by duration of gestation but other biological factors such as gender, birth order, mother’s age, obstetric complications etc. also play a role. The present study was undertaken in a Speciality hospital in Bangalore, South India to determine the average birth weight and gestation as well the positive correlation of biological factors including complications of pregnancy such as PIH and Diabetes.

Materials and Method

All 2789 singleton live born babies included in this study among a total 2808 consecutive births from January 2015 to May 2017, at Shifaa Hospital, a multispecialty center catering mainly to the middle and lower socioeconomic strata, in the metropolitan city of Bangalore. Exclusion criteria were 19 twin deliveries and 18 stillbirths. All women received adequate prenatal care and gestational age assessed by Last Menstrual Period (LMP) correlated with Crown-rump length (CRL) measurement by ultrasound examination undertaken within 18-20 weeks to establish fetal age when menstrual dates were unknown or in pregnancies with discrepancy greater than ± 7 days. If CRL and menstrual dates agreed to within the normal range of error (± 7 days), then LMP was used to establish fetal age.

Birth weight was recorded within 24 h of birth on a digital weighing machine accurate up to 10 g. Sources of data were Labor room register, new-born register and maternal and neonatal records when required. Data was entered into EPIDATA entry software, 3.1.2701.2008 and data analysis with statistical significance was done using STATA version 13.1.

Results

There were a total of 2808 deliveries during the 29 month period from 1st Jan 2015 to 31st May 2017, exclusion criteria were 19 twin deliveries and 18 stillbirths. Among the 2789 singleton live births included in the study, birth weight was missing for 2.9% (n=81), gestation was missing for 8.9% (n=251), gender was missing for 3.7% (n=105), birth order was missing for 4.1% (n=116) and mother’s age was missing for 7.3% (n=206).

Infants with normal birth weight (NBW) ≥ 2500 g comprised 80.9% (n=2191) among which infants weighing 2500-3999 g comprised 79.8% (n=2163), of whom 38.1% (n=1032) weighed 2500-2999 g, 34.1% (n=936) weighed 3000-3499 g and 7.2% (n=195) weighed 3500-3999 g. NBW 2500-3999 g had mean gestation of 38.7 ± 1.2 weeks, High birth weight (HBW) ≥ 4000 g comprising 1% (n=28) had mean gestation of 39.1 ± 1.2. This difference was not statistically significant (NS). However mean gestation in LBW<2500 g 37.1 ± 2.3 and NBW ≥ 2500 g being 38.7 ± 1.2 weeks was statistically significant (P<0.0001).

Term new-borns ≥ 37 weeks comprised 88.3% (n=2243) and preterm <37 weeks was 11.6% (n=295). There were no post term births beyond 42 weeks. The mean birth weight for term and preterm babies was 2938 ± 442 g and 2330 ± 585 g, respectively, a difference of 608 g being highly statistically significant (P=0.0001). Most term infants 39% (n=875) weighed 2500-2999 g contrasted with preterm 36.6% (n=108) weighing less between 2000-2499 g.

Sex ratio revealed 984 females to 1000 male infants. However more nearly half of male babies 47.4% (n=640) weighed ≥ 3000 g when compared to about one-third female babies 38.4% (n=508). The mean birth weight for male and female was 2916 ± 501 g and 2835 ± 481 g respectively, a difference of 81 g being statistically significant (P<0.0001). However slightly more males 12.6% (n=160) were premature <37 weeks compared to females 10.3% (n=130). The mean gestation for male and female was 38.3 ± 1.7 and 38.4 ± 1.6 weeks, respectively, was statistically significant (P=0.02) as shown in Tables 1 and 2.

Criteria Birth weight in grams (g)    
= 999 1000-1499 1500-1999 2000-2499 2500-2999 3000-3499 3500-3999 >4000 Total Mean Birth Wt. (g) ± S.D. P Value
Singleton births 15 30 61 411 1032 936 195 28 2708 2873 ± 498  
Gestation <37 7 21 39 108 83 31 6 0 295 (11.6) 2330 ± 585 P=0.0001
In weeks >37 8 9 18 283 875 852 174 24 2243 (88.3) 2938 ± 442
Sex Male 4 15 29 182 480 506 115 19 1350 (50.3) 2916 ± 501 P=0.0002
Female 8 13 32 225 548 421 78 9 1334 (49.7) 2835 ± 481
Birth Order First Born 3 10 28 155 365 257 52 6 876 (32.7) 2817 ± 484 P=0.0001
Later Born 12 20 32 252 648 672 139 22 1797 (67.2) 2899 ± 503
Mother’s Age/year <30 13 23 50 335 829 722 143 15 2129 (82.4) 2857 ± 492 P=0.001
>30 2 6 8 56 159 172 41 10 454 (17.5) 2941 ± 509
Mode of Delivery Normal 9 17 32 222 566 505 76 8 1435 (52.9) 2848 ± 477 NS
Elective LSCS 1 3 5 50 160 135 36 8 398  (14.6)
Emergen LSCS 5 10 24 125 257 237 72 9 739  (27.3) 2850 ± 529
PIH Yes 2 5 9 27 36 44 13 0 136  (5.0) 2730 ± 511 P=0.0006
No 13 25 52 385 996 891 182 28 2572 (95.0) 2881 ± 496
Diabetes Yes 0 2 0 14 41 44 19 4 124 (4.6) 3039 ± 553 P=0.0001
No 15 28 61 398 991 892 175 24 2584 (95.4) 2853 ± 515

Table 1: Distribution of birth weight in relation to biological criteria.

Criteria Gestational Age in weeks    
<37 37-40 40+ Total Mean Gestation in weeks ± S.D. P Value
No. of births   295 (11.6%) 1696 (66.8) 274 (10.8) 2538 (100) 38.2 ± 2  
VLBW <1500 g 28 (62.2) 13 (28.8) 4 (8.8) 45 (1.77) 33.7 ± 4.2 P<0.001
LBW 1500-2500 g 147 (32.8) 285 (63.6) 16 (3.5) 448 (17.6) 37.3 ± 1.8
NBW 2500-4000 g 120 (5.9) 1653 (81.8) 248 (12.27) 2021 (79.6) 38.7 ± 1.2 NS
HBW = 4000 g 0 18 (75) 6 (25) 24 (0.94) 39.1 ± 1.2
Sex Male 160 (12.6) 982 (77.5) 125 (9.86) 1267 (50.1) 38.3 ± 1.7 P=0.02
Female 130 (10.3) 984 (78.0) 147 (11.6) 1261 (49.9) 38.4 ± 1.6
Birth Order First Born 75 (8.9) 645 (77.2) 115 (13.7) 835 (32.8) 38.5 ± 1.5 P<0.001
Later Born 220 (12.8) 1334 (77.9) 157 (9.1) 1711 (67.2) 38.2 ± 1.6
Mother’s Age = 30 years 238 (9.6) 1572 (75.1) 229 (11.2) 2039 (82.7) 38.4 ± 1.6 P=0.005
>30 years 79 (11.5) 343 (80.7) 33 (7.7) 425 (17.2) 38.1 ± 1.5
Mode of Delivery Normal 132 (9.8) 1062 (77.8) 170 (12.4) 1364 (56.1) 38.5 ± 1.6 P<0.001
Elective LSCS 43 (11.4) 314 (83.5) 19 (5.0) 376 (35.2) 38.1 ± 1.3
Emergency LSCS 114 (16.5) 510 (73.9) 66 (9.5) 690 (64.7) 38.1 ± 1.8
PIH Yes 33 (24.8) 90 (67.7) 10 (7.5) 133 (5.1) 37.5 ± 2.0 P<0.001
No 263 (10.8) 1902 (78.3) 265 (10.9) 2430 (94.8) 38.4 ± 1.6
Diabetes Yes 27 (21.9) 93 (75.6) 3 (2.4) 123 (4.8) 37.7 ± 1.4 P<0.001
No 269 (11) 1899 (77.8) 272 (11.1) 2440 (95.2) 38.4 ± 1.6

Table 2: Gestational age characteristics of new-borns <37 weeks, 37-40 weeks and 40+ weeks.

First birth infants comprised 32.7 (n=876), while second and later births comprised two-thirds 67.2% (n=1797). However 37.7 % (n=1797) of later births weighed more 3000-3499 g, compared to 41.6% (n=876) first birth infants who weighed less 2500-2999 g. The mean birth weight for first and later birth infants was 2817 ± 484 g and 2899 ± 503 g, respectively, a difference of 82g being highly statistically significant (P=0.0001). Prematurity was low 8.9% (n=75) in first births compared to12.8% (n=220) of later births. The mean gestation in first and later birth infants was 38.5 ± 1.5 and 38.2 ± 1.6 weeks, respectively, the difference being statistically significant (P<0.001).

Teenage mothers, 19 years and below comprised 8.5% (n=220), majority 39.1% (n=1012) were 20-24 years and 34.7% (n=897) between 25-29 years, thus nearly three fourth 73.8 percent of mothers were in their twenties 20-29 years, 14.4% (n=373) older mothers 30-34 years comprised and 3.1% (n=81) were above 35 years. Hence majority 82.4% (n=2129) were young mothers below 30 years and 17.5% (n=454) were 30 years and above.

Most 38.9% (n=826) infants of young mothers below 30 years weighed 2500-2999 g while 37.8% (n=172) infants of older mothers ≥ 30 years weighed more 3000-3499 g. The mean birth weight in young mothers below 30 years was 2857 ± 492 g compared to 2941 ± 509 g for older mothers, difference of 84 g was highly statistically significant (P=0.001). However older mothers ≥ 30 years had higher incidence of prematurity 11.5% (n=79) compared to 9.6% (n=238) in younger mothers, and mean gestation of 38.1 ± 1.5 and 38.4 ± 1.9 weeks respectively was statistically significant (P=0.005).

Another variable of mode of delivery, normal vertex vaginal delivery occurred in half 53.2% (n=1364) followed by Caesarean Sections (C.S.) in 41.6% (n=1066), Vacuum extractions 3.5% (n=97) and Low Perineal Forceps (LPF) delivery 1.4% (n=39). Breech presentation occurred in 2.5% (n=50), but only 0.5% (n=10) were assisted vaginal breech delivery and remaining 1.5% (40) by emergency C.S. However among a total 1066 C.S, most 64.7% (n=690) were emergency C.S and 35.2 % (n=376) elective or planned C.S. Repeat C.S. were performed in one third 32.6% (n=348). The mean birth weight for normal deliveries was 2831 ± 477 g and C.S. 2850 ± 529 g, difference of 19 g being statistically significant (P=0.047). Incidence of prematurity was higher 16.5% (n=114) in emergency C.S. compared to 11.4% (n=43) in elective C.S. The mean gestation for emergency C.S. and elective C.S. was 38.1 ± 1.3 and 38.1 ± 1.8 weeks respectively was not significant (NS) (P=0.94). However the mean gestation in infants delivered normally compared to overall C.S. was 38.5 ± 1.6 and 38.1 ± 1.8 weeks respectively being statistically significant (P<0.001).

The incidence of obstetric complications of Pregnancy Induced Hypertension (PIH) was 5% (n=136) and Diabetes 4.6% (n=124). Most infants 32.3% (n=44) with obstetrical complications of PIH and 35.4% (n=44) with maternal diabetes weighed between 3000-3499g. The mean birth weight with and without PIH complicating pregnancy was 2730 ± 511 g and 2881 ± 496 g, respectively, the difference of 151g being highly statistically significant (P=0.0006). However infants of diabetic mothers weighed more, mean birth weight 3039 ± 455 g compared to 2853 ± 515 g in non-diabetic mothers, a difference of 186 g, was highly statistically significant (P=0.0001).

Incidence of prematurity was high 24.8% (n=33/total 136) with PIH complicating pregnancy compared to 21.9% (n=27/total 124) infants of diabetic mothers who had low mean gestation of 37.5 ± 2.0 and 37.7 ± 1.4 weeks, respectively compared to 38.4 ± 1.6 in uncomplicated pregnancy being statistically significant (P<0.001).

Discussion

In this study 2789 singleton live births, had mean birth weight of 2873.73 ± 498.6 g, mean gestation 38.2 ± 2 weeks and LBW <2500 g 19.1%. A study from North India also reported mean birth weight 2725.40 ± 424.64 g, mean gestation of 38.1 ± 1.9 weeks and LBW 19.8 % (4). Term infants ≥ 37 weeks comprised 88.3% (n=2243) and 11.6% (n=295) preterm in present study compared to North India with 76.8% term and 23.2% preterm, respectively. (4). Mean birth weight for term 2938 ± 442 g and preterm 2330 ± 58 5 g, difference of 608 g was statistically significant (P=0.0001). In the present study VLBW <1500 g comprised 1.6% had mean gestation of 33.7 ± 4.2 weeks as compared to LBW 1500-2499 g with 37.3 ± 1.8 weeks being statistically significant (P<0.001).

According to UNICEF LBW rates were 7%, 16% and 19%, respectively in industrialized, developing and least developed countries [6]. LBW and preterm birth rates were 17.0% versus 5.5% and 12.3% versus 6.9%, respectively in South India and Nova Scotia, Canada [7]. Unlike in Western countries, where the incidence of LGA babies has spiralled upward, it has remained nearly at the same level over one and a half decades, reported in South India, despite improvements in socioeconomic status and obstetric care, the mean birth weight 2846 g in 1996 remained at 2907 g in 2010 over 15 years, with a difference of only 61 grams [5,7]. Thus Indian women will continue to have a high incidence of LBW up to 27.4% reported in rural India [8] though it is unclear whether high rates of LBW in South Asia are due to poor fetal growth or short pregnancy duration [9]. In contrast western population report a high mean birth weight of 3446 g in U.S born white women, a difference of 573 g compared to the present study [10]. Globally of the 20 million LBW representing 15.5% of all births, 95.6% are in developing countries with India alone accounting for 40% LBW in developing countries [11], however in developing countries the majority of LBW new-borns have intrauterine growth restrictions rather than being born preterm [12] hence a redefinition of LBW is indicated in ethnic Asians so as to more accurately identify prematurity as cause of LBW [12].

Sex ratio was 984 females to 1000 male infants; a skewed 804 female/1000 male infants was reported from North India [4]. Male babies had higher mean birth weight of 2916 ± 501 compared to female babies with 2835 ± 481, difference of 81 g being highly statistically significant (P<0.0001), similarly also reported in another study male weighed 45 g more than female babies, mean birth weight being 2934 g and 2889 g, respectively [4]. However more males 12.6% (n=160) were born preterm <37 weeks, compared to females 10.3% (n=130). The mean gestation in males and females being 38.3 ± 1.7 and 38.4 ± 1.6 respectively also statistically significant (P=0.02).

First births were lighter with mean birth weight of 2817 ± 4 84 g compared to 2899 ± 503 g in later born infants, difference of 82 g being statistically significant (P=0.0001). However more 12.8% (n=220) later births were preterm <37 weeks, compared to 8.9% (n=75) first birth infants, with a mean gestation of 38.2 ± 1.6 weeks and 38.5 ± 1.5 weeks, respectively being statistically significant (P<0.001). Other study also reported later birth infants being heavier by 100g with the mean birth weight of 2880 g compared to 2770 g for first born babies [4].

Infants of young mothers 20-29 years had lower mean birth weight of 2857 ± 492 g compared to 2941 ± 509 g in older mothers ≥ 3 0 years, a difference of 84 g being statistically significant (P=0.001). However older mothers ≥ 30 years had higher incidence of prematurity 11.5% (n=79) compared to 9.6% (n=238) infants born to younger mothers. The mean gestation for mothers <30 and ≥ 30 years was 38.4 ± 1 and 38.1 ± 1.5 weeks, respectively being statistically significant (P=0.005).

Caesarean section rate increased to 41.6%, majority being emergency section 64.7% and in 35.2 % elective or planned sections. Repeat section was performed in one third 32.6%. In contrast other studies report a low cesarean rate of 15.3% in North India [4] and 3.1% in 1986-87 increasing to 10.9% in 2004-2005 in South India while in Nova Scotia, Canada it increased from 20.2% to 28.4% [5]. Understandably though emergency cesarean section delivery was related to a higher incidence of prematurity 16.5% compared to 11.4% among elective sections, the mean gestation between emergency and election sections was not statistically significant (P=0.94), contrasted with mean gestation of 38.5 ± 1.6 weeks in infants with normal delivery compared to 38.1 ± 1.6 C.S being statistically significant (P<0.001). in contrast infants of normal delivery had lower mean birth weight of 2848 ± 477 g to 2850 ± 529 g in caesarean births, difference of 19g being statistically significant (P=0.047). A higher incidence of LBW 22.1% was noted for emergency sections compared to14.8% in elective sections. Thus the risk for LBW and prematurity was higher with emergency sections.

Obstetric complications of PIH and Diabetes had higher incidence of prematurity 24.8% and 21.9%, respectively with mean gestation of 37.5 ± 2.0 weeks and 37.7 ± 1.4 weeks respectively compared to 38.4 ± 1.6 weeks in uncomplicated pregnancy of statistical significance (P<0.001). Similarly a low mean birth weight of 2730 ± 511 g in infants with PIH complicating pregnancy contrasted with higher mean birth weight of 3039 ± 455 g in infants of diabetic mothers, in contrast pregnancy uncomplicated with PIH and diabetes had mean birth weight of 2881 ± 496 and 2853 ± 515 g, respectively, this difference of 151 g and 186 g, respectively being highly statistically significant (P=0.0006) in the former and (P<0.001) in the latter.

Conclusion

Mean birth weight is a good indicator for any population to determine outcome of new-borns. This study reveals that though duration of gestation had a major impact on birth weight other biological factors such as gender with male babies, second and later births, as well as infants born to older mothers tended to have statistically significantly higher mean birth weight. In contrast infants of mothers with PIH registered lower mean birth weight to infants of diabetic mothers with higher mean birth weight but significantly shortened gestation.

Mean birth weight is a good indicator for any population to determine outcome of new-borns. This study reveals that though duration of gestation had a major impact on birth weight other biological factors such as gender with male babies, second and later births, as well as infants born to older mothers tended to have statistically significantly higher mean birth weight. In contrast infants of mothers with PIH registered lower mean birth weight to infants of diabetic mothers with higher mean birth weight but significantly shortened gestation compared to uncomplicated pregnancy.

Funding

No External Funding.

References

Citation: Christopher GL (2018) The Effect of Biological Factors on Birth Weight and Gestation in South Indian New-Borns. J Pediatr Neurol Med 3: 130. DOI: 10.4172/2472-100X.1000130

Copyright: ©2018 Christopher GL. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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