Effects of short birth spacing on birth-order differences in child stunting: Evidence from India

Do firstborn children have a height advantage? Empirical findings have found mostly that, yes, second or higher-order children often lag behind firstborns in height outcomes, especially in developing countries. However, empirical investigations of birth-order effects on child height overlook the potential impact that birth spacing can have. We provide an explanation for the negative birth-order effect on stunting outcomes for young Indian children and show it is driven by short preceding-birth spacing. We find that firstborn children are taller than children of higher birth order: The height-for-age gap for third (or higher)-order children is twice the gap for children second in birth order. However, this pattern is observed when spacing between later-born children and their immediate elder siblings is fewer than 3 y. Interestingly, the firstborn height advantage disappears when later-born children are born at least 3 y after their elder siblings. Thus, our findings indicate that spacing length between children explains differences in height, over birth order. Although India’s family planning policy has resulted in a substantial reduction in total fertility, its achievement in spacing subsequent births has been less impressive. In showing that spacing can alleviate or aggravate birth-order effects on attained height, our study fills an evidence gap: Reducing fertility alone may not be sufficient in overcoming negative birth-order effects. To reduce the detrimental effects of birth order on child stunting, policy responses—and therefore research priorities—require a stronger focus on increasing the time period between births.

Child undernutrition continues to be a problem in low-and middle-income countries, and adversely affects child survival and well being (1). While child undernutrition is gauged by several indicators, stunting—a key marker of chronic undernutrition obtained by comparing child height with that of children in the same age group in a healthy reference population—is at the forefront of discussion because of its vast prevalence across all developing regions and its important consequences for health and development. Almost all of stunting takes place in the first 1,000 d from conception to 2 y of age, but its consequences follow throughout adulthood. These consequences are largely irreversible, making stunting an extremely critical condition (2, 3). Children who are stunted are vulnerable to disease and mortality during childhood and run a much higher risk of developing deficits in later-life outcomes, including in adult height, cognitive and intellectual ability, and as a consequence, on schooling attainment, productivity, and earnings (4–10). Furthermore, if stunting is accompanied by excessive weight gain later in childhood, there is an increased risk of developing adult obesity and nutrition-related chronic diseases, including cardiovascular disease, stroke, and type 2 diabetes in adult life (see, for example, ref. 6). In addition, stunted girls carry additional risk of having adverse pregnancy outcomes and reproductive complications as adults, leading to detrimental intergenerational effects (11, 12). Nevertheless, stunting is preventable, and reducing it is an important component of overall development for the well being of children.In recognition of the high social and economic costs of stunting, efforts are ongoing to address this public health issue, including programs aimed at reducing poverty and inequality, improving dietary intake and access to healthcare services, and improving the hygiene environment. Childhood stunting has declined by 35% from a global estimate of 253 million in 1990, with over 90 million children protected from suboptimal growth and a large number of child deaths prevented. However, this decrease is small relative to the overall burden, as over 161 million children under 5 y were reported to be stunted in 2011 (13). Furthermore, there is a large disparity in numbers across regions, with the highest number of over 69 million stunted children living in South Asia and with India bearing 90% of this regional burden (14). Thus, although stunting levels have been reduced, the progress has been both uneven and suboptimal (15). There is need to develop strategies, policies, and programs tailored to local conditions, which in turn require a case-by-case approach to identify what other conditions may be predisposing children to poor height in certain regions, and also, within regions.Birth order—an indicator of a child’s position in the age hierarchy of siblings—has been used time and again to explain variation in height outcomes in children. Children born to the same parents share the same genetic make-up; yet, the order in which they are born exposes them to different biological and behavioral environments (16, 17). Through differences in health endowments and parental investments, birth order often affects the health and nutritional outcomes of children. Hence, birth-order effects reflect differences in the unshared environment within a family. The literature on child stunting has provided significant evidence from across countries that children of lower birth order are at an advantage, compared to children of higher birth order. Firstborn children are taller compared to those born subsequently, and this height advantage increases sharply over the higher order of birth of siblings. Explanations for the firstborn height advantage have addressed issues, such as better health endowments of the firstborn at birth and parental favoritism toward some offspring over others—usually the eldest son—generating more prenatal and postnatal investments, greater time investment in child care, longer duration of breastfeeding, and also affecting the desire for having more children (18–24).However, an important factor in assessing the birth-order effects on child health and nutritional outcomes is the length of interval between two consecutive births: That is, birth spacing. A wealth of studies have shown that a short length of birth spacing is associated with higher risk of maternal mortality and adverse subsequent birth outcomes, such as child mortality, preterm birth, small for gestational age, and low birthweight, though the degree to which the relationship holds varies substantially across countries (25–29). These associations stem from the biological factor commonly referred to as maternal depletion syndrome (26, 30). Closely spaced pregnancies may not allow sufficient time for the mother to restore her depleted micronutrient and macronutrient stores from the previous birthing, which in turn may reduce her ability to provide a favorable fetal growth environment in subsequent pregnancies and sufficient breast milk production postdelivery. Literature also suggests short birth spacing is associated with suboptimal parental care practices, which adversely affect the health and nutritional outcomes of siblings born close to each other. For example, the birth of a new baby may reduce the parental care time devoted to older siblings, as well as result in poor postnatal investment; similarly, a new pregnancy may reduce or curtail breast milk production, which may lead to suboptimal feeding for older siblings.While the aforementioned channels show the potential for longer birth spacing to influence nutritional outcomes of children more positively, especially for the later born, empirical inquiry into the spacing order linkages is limited. We believe that birth order and height linkage can be better understood by examining the interaction between birth order and birth spacing. Using an illustrative example of India in this paper, we demonstrate that the negative association between increasing birth order and child height is driven by the short length of interval between births. We link height-for-age standardized scores (HAZ) of children under 5 y, recorded in the latest Indian Demographic and Health Survey (DHS), to an indicator of birth order, disaggregated by the length of preceding birth spacing. When birth order is considered alone, we find that firstborn children on average are taller than children of higher birth order. This result is consistent with previous research on birth order. However, we discover noteworthy changes in the patterns of the HAZ gap between firstborn and subsequent children on combining birth order with preceding birth spacing. We find that the firstborn height advantage is significant if birth spacing between the higher-order child and its immediate elder sibling is less than 3 y, and this advantage gets steeper with increasing order of birth; that is, the height advantage for firstborns, compared to children from third or higher-order births, is almost twice the height advantage for firstborns, compared to children of second-birth order. Interestingly, if the birth spacing between the higher birth-order child and its immediate elder sibling is 3 or more years, the firstborn height advantage disappears and becomes insignificant. This is true with respect to the gap for all higher birth-order children. Thus, higher birth-order children, on average, are as tall as firstborn children if they are appropriately spaced. Our results emphasize the importance of time between births in determining height outcomes of young children, over birth order, and demonstrate how spacing length may weaken or strengthen the birth-order effect on child height. Designing and implementing policies and interventions that affect knowledge and attitude toward healthy spacing could significantly impact the health, nutrition, and accomplishments of young children.However, we emphasize at the outset that our analysis is exploratory in nature. An ideal dataset for comparing height outcomes across birth orders would require longitudinal data, recording all pregnancies conceived by a woman with predelivery and postdelivery information related to healthcare, as well as feeding practices for every living child. Because of the absence of datasets that cover all these aspects, we rely on DHS data, which are closely but imperfectly suited to the question at hand. The nature of DHS is such that anthropometry is recorded only for children below 5 y, and for many healthcare and dietary intake variables the information is collected only for the youngest child born to the mother. Hence, the reduced sample size and data limitations preclude our ability to establish causality. However, the large sample size is sufficient to assess subgroup and interaction effects. We address several possible biases or limitations of using survey data with additional analyses.     

极低出生体质量儿早期规范补铁的临床观察

目的探讨早期规范补铁对极低出生体质量儿病情转归的影响,以避免发生不可逆的神经系统损伤。方法选择2014年6月-2015年12月在防城港市第一人民医院住院的极低出生体质量儿76例为研究对象,按数字表法随机分为试验组38例和对照组38例,对照组予常规治疗,按指南补铁;试验组也予常规治疗,同时按血清铁(SI)、血清铁蛋白(SF)和总铁结合力(TIBC)水平早期补铁。观察两组感染控制时间、新生儿神经行为评分(NBNA)恢复情况。结果试验组总有效率为84.21%高于对照组的65.79%,两组比较差异有统计学意义(χ~2=4.047,P<0.05)。试验组感染控制时间、NBNA恢复时间、住院时间、住院费用[(6.71±2.47)d、(77.53±9.11)d、(23.63±8.86)d、(19 829.95±12 855.04)元]等均少于对照组[(10.47±3.68)d、(77.66±8.67)d、(31.03±15.35)d、(28 405.82±15 213.96)元],差异均有统计学意义(t=-5.728、-3.933、-2.615、-2.636,均P<0.05)。结论早期规范补铁对极低出生体质量儿病情转归有较好的促进作用,有助于神经系统的发育,缩短住院时间,降低住院费用。     

牙周龈下螺旋体和早产低体重儿关系的初探

目的初探牙周状况、龈下螺旋体和早产低体重儿(PLWB)发生之间的关系。方法从住院病例库中按严格标准选出PLWB组(49例)和Control组(20例),电话召回填写调查问卷、单盲检查口腔牙周情况(PLI、BI、PD)并计数指数牙(16、21、24、36、41、44)的CAL和龈下螺旋体比例,用统计学软件处理最终数据。结果PLWB组83.7?L>0,Control组55.0%,P<0.05;两组所有指数牙的PD、CAL和龈下螺旋体比例均为PLWB组大于Control组,P<0.05都是下颌牙位。结论PLWB组牙周破坏倾向于比Control组更重;龈下螺旋体或许可以充当一个粗略的PLWB预示指标。     

母体牙周病与新生儿低体质量关系的初步探讨

目的 :探讨母体牙周病与新生儿体质量 (体重 )不足是否有相关性。方法 :调查 2 0 7名产后 4d母亲。新生儿体质量不足 :体质量 <2 50 0 g或者伴有孕期 <37周、胎膜早破等妊娠不良情况 (n =1 0 6)。对照组 :新生儿体质量≥ 2 50 0 g ,正常分娩 (n =1 0 1 )。每位受试者均接受牙周检查并记录临床有关数据。 结果 :LWN组牙周病明显重于对照组 ,经统计学处理P <0 .0 0 1。 2 0 7名母亲牙周袋深度和牙龈指数与新生儿体质量呈负相关 (rGI=- 0 .37,P <0 .0 1 ;rPD=- 0 .1 9,P <0 .0 1 )。结论 :母体牙周病作为新生儿低体质量的危险因素之一尚需进一步研究 ,本调查结果显示母体的牙周病与新生儿低体质量呈低度相关     

Periodontal treatment during pregnancy decreases the rate of adverse pregnancy outcome: a controlled clinical trial

Objectives

The aim of this study was to evaluate the effects of non-surgical treatment of periodontal disease during the second trimester of gestation on adverse pregnancy outcomes.

Material and Methods

Pregnant patients during the 1^st and 2^nd trimesters at antenatal care in a Public Health Center were divided into 2 groups: NIG – "no intervention" (n=17) or IG- "intervention" (n=16). IG patients were submitted to a non-surgical periodontal treatment performed by a single periodontist consisting of scaling and root planning (SRP), professional prophylaxis (PROPH) and oral hygiene instruction (OHI). NIG received PROPH and OHI during pregnancy and were referred for treatment after delivery. Periodontal evaluation was performed by a single trained examiner, blinded to periodontal treatment, according to probing depth (PD), clinical attachment level (CAL), plaque index (PI) and sulcular bleeding index (SBI) at baseline and 35 gestational weeks-28 days post-partum. Primary adverse pregnancy outcomes were preterm birth (<37 weeks), low birth weight (<2.5 kg), late abortion (14-24 weeks) or abortion (<14 weeks). The results obtained were statistically evaluated according to OR, unpaired t test and paired t test at 5% significance level.

Results

No significant differences were observed between groups at baseline examination. Periodontal treatment resulted in stabilization of CAL and PI (p>0.05) at IG and worsening of all periodontal parameters at NIG (p<0.0001), except for PI. Significant differences in periodontal conditions of IG and NIG were observed at 2nd examination (p<0.001). The rate of adverse pregnancy outcomes was 47.05% in NIG and 6.25% in IG. Periodontal treatment during pregnancy was associated to a decreased risk of developing adverse pregnancy outcomes [OR=13.50; CI: 1.47-123.45; p=0.02].

Conclusions

Periodontal treatment during the second trimester of gestation contributes to decrease adverse pregnancy outcomes.