Background: Lipids in human milk (HM) provide the majority of energy for developing infants, as well as crucial essential fatty acids (FA). The FA composition of HM is highly variable and influenced by multiple factors. We sought to increase understanding of the variation in HMFA profiles and their development over the course of lactation, and after term and preterm delivery, using a pooled data analysis. Objective: To review the literature and perform a pooled data analysis to qualitatively describe an extensive FA profile (36 FAs) in term and preterm colostrum, transitional -and mature milk up to 60 days postpartum. Design: A Medline search was conducted for HMFA profile data following term or preterm delivery. The search was confined to English language papers published between January 1980 and August 2018. Studies reporting original data, extensive FA profiles in HM from healthy mothers were included. Weighted least squares (WLS) means were calculated from the pooled data using random or fixed effect models. Results: Our pooled data analysis included data from 55 studies worldwide, for a total of 4374 term milk samples and 1017 preterm milk samples, providing WLS means for 36 FAs. Patterns in both term and preterm milk were apparent throughout lactation for some FAs: The most abundant FAs (palmitic, linoleic and oleic acid) remained stable over time, whereas several long-chain polyunsaturated FAs (including ARA and DHA) seemed to decrease and short-and medium-chain FAs increased over time.Conclusions: High heterogeneity between individual studies was observed for the reported levels of some FAs, whereas other FAs were remarkably consistent between studies. Our pooled data suggests that specific FA categories fluctuate according to distinct patterns over the course of lactation; many of these patterns are comparable between term and preterm milk.

Objective: To investigate whether bone resorption markers change during pregnancy and lactation, and how they are correlated with human placental lactogen (hPL) and PRL. Subjects: Young women before pregnancy, during pregnancy and during a 12-month post-delivery period (study group; n = 22); and age- and weight-matched normal cycling women (control group; n = 22) for a 20-month-period participated in the study. Results: In the study group, women both during pregnancy (from the 8th up to the 38th week) and during a 6-month period of lactation, pyridinoline and deoxypyridinoline urinary levels were significantly higher than those of pre-pregnancy and control women. They returned to basal values at the 12th post-delivery month. During pregnancy there were early and late peak increases, at the 8th and 32nd week, respectively. At the 32nd, 34th, 36th and 38th week of pregnancy, pyridinoline and deoxypyridinoline urinary values were significantly correlated with hPL serum levels. Conclusions: During pregnancy the maternal bone resorption seems to vary critically at early and late stages. A complete reversal of these variations seems to occur after lactation. Further studies could evaluate if changes in placental function are capable of differently interfering with maternal bone resorption.