Maternal Plasma Concentrations of Per- and polyfluoroalkyl Substances and Breastfeeding Duration in the Norwegian Mother and Child Cohort

Abstract

Background: Per- and polyfluoroalkyl substances (PFASs) have been widely produced, many of them persist in the environment, and have been associated with various health effects. Previous studies have identified inverse associations between perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and breastfeeding duration, but have been limited in investigation of other PFASs.

Methods: We measured the associations between plasma concentrations of 9 different PFASs and cessation of breastfeeding before 3 and 6 complete months using women from the Norwegian Mother and Child Cohort Study (MoBa). The study population includes 1716 primarily nulliparous women from two previous studies of MoBa participants, enrolled from 2003-2007. The association was measured using Cox proportional hazards model. Mixtures analyses were performed using Elastic net regularization to identify interactive effects and control for co-pollutant confounding.

Results: Concentrations of PFASs in this population were lower than concentrations in the previous studies on this topic. We found associations between increasing concentrations of perfluorononanoic acid (PFNA), perfluorodecaconic acid (PFDA), perfluoroundecanoic acid (PFUnDA) and decreased breastfeeding cessation (increased duration). The strongest associations were seen between PFDA and PFUnDA and cessation before 3 months: (both hazard ratios = 0.73, 95% confidence intervals: 0.62, 0.86). In our population, the other PFASs appeared to be unassociated with breastfeeding cessation. The mixtures analyses identified meaningful interactions between PFUnDA:PFDA, perfluorohexane sulfonate (PFHXS):PFOA and PFOA:PFOS.

Conclusions: The identification of associations between previously unexamined PFASs concentrations and increased breastfeeding duration is novel and may be explained by differences in transplacental transfer rates.

Figure 1.

DAG for MoBa population.

Figure 2.

Adjusted hazard ratios (95% CIs) for cessation of breastfeeding at (a) 3 months and (b) 6 months in association with quartiles of plasma concentrations for per- and polyfluoroalkyl substances. (a) Model was adjusted for parity (parous vs. nulliparous), previous breastfeeding duration (continuous, months), maternal age at birth (continuous), smoking during pregnancy (any vs. none), prepregnancy BMI (underweight, normal, overweight, obese), and prior study status (subfecundity control, subfecundity case, preeclampsia control, subfecundity case). (b) Median concentrations of quartile 4 (n = 429) of PFASs and n cessation at 3 months: PFOA (3.97 ng/mL, n = 38); PFNA (0.79 ng/mL, n = 36); PFDA (0.22 ng/mL, n = 26); PFUnDA (0.39 ng/mL, n = 33); PFHxS (1.23 ng/mL, n = 39); PFHpS (0.27 ng/mL, n = 53); PFOS (19.84 ng/mL, n = 49).