The relationship of maternal body weight with iodine concentration in breast milk and cord blood and infant growth parameters

A total of 84 mothers (n=42) who had recently given birth in the Gynecology and Obstetrics Outpatient Clinic of Alanya Training and Research Hospital, normal (18,5-24,9 kg/m2) and overweight-obese (≥25 kg/m2) according to their pre-pregnancy BMI (n=42) and their infants participated in this study which was conducted to evaluate the relationship between maternal body weight and iodine concentration in breast milk and cord blood and growth parameters in the infant. A questionnaire form including information on socio-demographic characteristics, dietary habits, information on iodine use, biochemical parameters of the mothers, food record obtained by 24-hour recall method and information on food frequency questionnaire was applied and anthropometric measurements of women and infants (body weight, height, head circumference) were taken. In the postnatal period, cord blood and breast milk (colostrum) samples were collected and iodine measured by Sandell-Kolthoff reaction and leptin, adiponectin and IGF-I concentrations were measured by ELISA method. Breast milk iodine concentrations have been found to be <100 μg/L in both normal body weight and overweight-obese. Maternal dietary iodine intake, breast milk iodine concentration and cord blood iodine concentration were found to be 184,4±73,8 μg, 16,6±4,9 μg/L and 32,9±4,8 μg/L, in normal weight and 186,6±72,3 μg, 18,2±6,7 μg/L and 31,9±6,7 μg/L, in overweight-obese. Maternal dietary iodine intake and breast milk iodine concentration of overweight-obese were higher than those of women with normal weight (p>0,05). There was no significant correlation between maternal dietary iodine intake and cord blood and breast milk iodine concentrations of women in both groups. The iodine concentration in breast milk of normal body weight (19,7±8,4 μg/L) and overweight-obese (23,8±4,7 μg/L) women who reported using iodized salt was found to be higher (p<0,05) than that of women who reported not using iodized salt (16,1±5,0 μg/L, 7,2±5,9 μg/L). There was a positive correlation between BMI before and after pregnancy and breast milk iodine and a negative correlation with cord blood iodine (p>0,05). Adiponectin and IGF-I in breast milk and cord blood of overweight-obese women (93,5±78,2 mg/L, 201,4±170,5 mg/L; 290,7±192,8 ng/mL, 325,7±235,3 ng/mL) concentrations in breast milk and cord blood of women with normal body weight (80,2±38,3 mg/L, 141,8±124,9 mg/L; 165,1±136,3 ng/mL, 271,6±187,7 ng/mL) were higher (p<0,05). Although adiponectin in cord blood and IGF-I in breast milk increased with increasing pre-pregnancy BMI, there was a negative correlation between weight gain during pregnancy and IGF-I in breast milk (p<0,05). There was a positive correlation between leptin, adiponectin, IGF-I and iodine in breast milk and cord blood (p>0,05). There was a positive correlation between cord leptin and breast milk IGF-I and cord leptin and breast milk iodine concentration (p<0,05). There was a positive correlation between breast milk adiponectin and infant body weight at birth and at 3 months and a positive correlation between breast milk leptin and infant body weight at 3 months (p<0,05). A positive correlation was found between breast milk IGF-I and infant's head circumference at birth and 3-month height, and a positive correlation was found between breast milk leptin and infant's 3-month weight gain (p<0,05). No significant relationship was between iodine in breast milk and anthropometric measurements of the infant. In the regression analysis, independent of confounding factors, an increase of 1 ng/mL in leptin in breast milk increased the body weight of the infant by 0,208 g (β=0,208; p=0,055), while an increase of 1 mg/L in adiponectin in breast milk increased the body weight of the infant by 0,291 g (β=0,291; p=0,009). In conclusion, a relationship was found between leptin and adiponectin in breast milk and infant body weight, and between IGF-I in breast milk and infant height, independent of maternal body weight. Although no significant relationship was found between iodine in breast milk and infant growth, more comprehensive studies are needed in this regard.