Department of Pediatric Newborn Medicine Maternal Obesity, 25(OH)D Concentration and Bone Density in Breastfeeding Dyads Sarbattama Sen, Annie Penfield-Cyr, Myla Ebeling, Bruce Hollis, Carol Wagner Assistant Professor of Pediatrics, HMS Neonatologist, Brigham and Women’s Hospital Department of Pediatric Newborn Medicine

Vitamin D and Maternal Health Vitamin D deficiency linked to metabolic syndrome, autoimmune disease, osteoporosis and mortality Obesity: risk factor for 25(OH)D deficiency In pregnancy, serum 25(OH)D is negatively related to BMI 0.4 ng/ml lower for each kg/m2 increase in BMI (Josefson, 2016)

Vitamin D and Infant Health Infants with vitamin D deficiency are at risk for rickets, asthma and overweight Breastmilk has low levels of vitamin D, further impacted by maternal factors During lactation, maternal 25(OH)D deficiency could affect both maternal and infant health Limited research on the effect of maternal obesity on the breastfeeding dyad

Objective To determine the association between maternal BMI and bone health in breastfeeding mother-infant dyads

Hypotheses We hypothesized that higher maternal BMI would be associated with lower: Maternal 25(OH)D concentration and bone mineral density (BMD) Infant 25(OH)D concentration and BMD

Methods N=234 exclusively breastfeeding mother-infant dyads enrolled in an RCT of maternal vitamin D supplementation Either received maternal vitamin D (6400IU) only or maternal (400IU) plus infant vitamin D (400 IU) 4-6 weeks post-partum at randomization (V1) and then 4 (V4) and 7 months (V7) after randomization Two sites (MUSC, 33oN and University of Rochester, 43oN) Exclusions: Maternal: preexisting type I or II diabetes, hypertension, parathyroid disease, uncontrolled thyroid disease, multiple gestation Infant: <35 weeks of gestation, >72 hours in the neonatal intensive care unit, any inborn error of metabolism, history of congenital anomalies Exposure: Maternal BMI Outcomes: Maternal and infant 25(OH)D concentrations measured using radioimmunoassay (Diasorin, MN) Bone density measured using DEXA (Hologic, MA) Statistical Analysis: We first compared sociodemographic variables by BMI category (WHO) Next, we examined the unadjusted associations between maternal and infant 25(OH)D concentration and BMD with maternal BMI using Pearson’s correlation We adjusted these associations for maternal race, education, insurance and center using multiple linear regression Stratified analysis conducted within 6400 IU and control groups

Maternal Characteristics Maternal demographic characteristics in women exclusively breastfeeding by BMI subgroup Maternal BMI, kg/m² Maternal Characteristic Total <25 kg/m² 25 - <30 kg/m² ≥30 kg/m² N at V1 (%) N at V4 (%) N at V7 (%) 234 181 130 74 (32) 73 (40) 59 (46) 88 (37) 55 (31) 33 (25) 72 (31) 53 (29) 38 (29) Mean (SD) Age at Enrollment (years) 28.4 (5.9) 28.1 (6.2) 28.5 (5.9) 28.5 (5.8) Mean (SD) Body Mass Index (kg/m²) V1 V4 V7 27.8 (4.8) 27.6 (5.8) 27.1 (5.9) 23.0 (1.4) 22.7 (1.5) 22.3 (1.8) 27.1 (1.5) 27.3 (1.5) 27.2 (1.3) 33.7 (3.5) 34.8 (4.8) 34.6 (4.6) Education = College Graduate N (%): Yes 92 (39) 35 (47) 34 (39) 23 (32) Insurance = Private N (%) 99 (42) 37 (50) 37 (42) 25 (35) Race/Ethnicity: N (%) Black Hispanic Asian White 60 (26) 70 (30) 5 (2) 13 (17) 22 (30) 3 (4) 36 (49) 18 (21) 30 (34) 2 (2) 38 (43) 29 (40) 18 (25) 0 (0) Parity: N (%) 1 >1 13 (6) 76 (32) 145 (62) 2 (3) 32 (43) 40 (54) 4 (5) 25 (28) 59 (67) 7 (10) 19 (26) 46 (64) Center: N (%) MUSC Rochester 132 (56) 102 (44) 43 (58) 31 (42) 54 (61) 35 (49) 37 (51) Dietary Maternal Vitamin D Intake (IU) Mean (SD) at V1 205.8 (126.0) 182.7 (120.8) 215.2 (135.8) 217.2 (117.5)

Baseline 25(OH)D status 25(OH)D concentration and percentage of participants with deficiency by BMI subgroup Maternal BMI, kg/m² Total N=234 <25 kg/m² N=74 25 - <30 kg/m² N=88 ≥30 kg/m² N=72 Maternal 25(OH)D concentration, ng/ml Mean (SD) 34.1 (13.3) 37.2 (14.8) 34.7 (13.6) 30.1 (10.0) Maternal 25(OH)D <20ng/ml % 13.2 8.1 12.5 19.4 Infant 25(OH)D concentration, ng/ml 14.2 (9.4) 15.5 (9.4) 13.1 (9.2) 14.5 (9.8) Infant 25(OH)D <20ng/ml 76.2 73.1 80.0 74.6

Maternal BMI and Maternal 25(OH)D V1 (4-10 weeks post-partum) V7 (7 months post-partum) Models N=234 β (95% CI) unadjusted Model 1 Model 2 -0.59 (-0.94, -0.24) -0.40 (-0.71, -0.09) -0.45 (-0.76, -0.14) Models N=170 β (95% CI) unadjusted Model 1 Model 2 -1.05 (-1.68, -0.43) -0.89 (-1.49, -0.29) -0.77(-1.39, -0.15) Model 1: adjusted for maternal race; Model 2: model 1+ education, insurance, center

Maternal BMI and Maternal Bone Density V1 (4-10 weeks post-partum) V7 (4 months post-partum) Models N=224 β (95% CI) unadjusted Model 1 Model 2 0.008 (0.005, 0.01) 0.006 (0.003, 0.01) Models N=129 β (95% CI) unadjusted Model 1 Model 2 0.007 (0.003, 0.01) 0.006 (0.003, 0.009) 0.007 (0.004, 0.011) Model 1: adjusted for maternal race; Model 2: model 1+ education, insurance, center

Maternal BMI and Infant 25(OH)D V1 (4-10 weeks) n=206 V4 (4 months) n=173 V7 (7 months) n=111

Maternal BMI and Infant Bone Density V4 (4 months) N=197 V1 (4-10 weeks) N=197 V7 (7 months) n=116 R² = 0.014 β=0.0007 (-0.001, 0.0005)

Associations in the 6400IU group Maternal BMI and Infant Bone Density V7, n=64

Conclusions In lactating women, higher BMI is: Associated with lower serum 25(OH)D concentrations But higher bone mineral density In infants, higher maternal BMI is: Not associated with infant 25(OH)D in immediate post-partum period However, 75% of infants were deficient by V1 Associated with lower infant 25(OH)D by 4 months post-partum Associated with lower infant bone density by 7 months post-partum Particularly in infants who received vitamin D supplementation through maternal milk only

Limitations High percentage of baseline deficiency Limited sample size in BMI subgroups At four and seven months, mothers and/or infants were receiving supplementation per randomization group

Future directions The long-term impact of maternal obesity on lactating dyads should be examined The other roles of vitamin D in maternal and infant health should be considered Maternal BMI should be considered as a potential risk factor for infant vitamin D deficiency Optimal maternal dosing of vitamin D based on BMI should be investigated

Acknowledgements Participating mothers and infants Funding Sources: Parent study: NIH 5R01HD043921, NIH RR01070, South Carolina Clinical & Translational Research (SCTR) Institute NICHD K23HD074648 (Sen)