1. 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

2. 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)

3. 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

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

5. 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

6. 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

7. 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)

8. 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

9. 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

10. 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

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

12. 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= (-0.001, )

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

14. 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

15. 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

16. 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

17. Acknowledgements Participating mothers and infants Funding Sources:
Parent study: NIH 5R01HD043921, NIH RR01070, South Carolina Clinical & Translational Research (SCTR) Institute
NICHD K23HD (Sen)