**5. Conclusions**

In conclusion, our results show that (1) the FA composition of colostrum and mature milk was different. Regardless of maternal weight, mature milk had lower levels of AA and DHA (among others) than colostrum; (2) Maternal obesity influenced the FA concentrations in breast milk. Overall, breast milk of mothers with a high BMI presented increased SFA levels and n6:n3 ratio, and decreased ALA, DHA and MUFA concentrations; and (3) The early supply of n6 and n3 PUFAs through colostrum influenced infant weight status and cognition, at 6 and 18 months of life, respectively. Infant BMIZ at 6 months of age was inversely associated with colostrum levels of n6 and n3 LC-PUFAs (e.g., AA and DHA) and positively associated with n6:n3 ratio. Depending on the maternal BMI, infant cognition may be positively affected by colostrum levels of LA, n6 PUFAs, DHA, n3 LC-PUFAs and ALA, and negatively affected by the n6:n3 ratio. Since the maternal pre-pregnancy weight can influence the breast milk FAs, which is related to the early nutritional status of the child and to health conditions throughout the life span, this study endorses the need for early preventive health care through diet and lifestyle. A healthy weight in women before, during and after pregnancy should be encouraged to promote beneficial FAs in breast milk and promote healthier future generations.

**Author Contributions:** The authors' responsibilities were as follows. C.C., M.C.L.-S. and A.I.C. designed the project. F.J.T.-E., L.G.-V., M.E.-M., M.T.S. were involved in participant recruitment, data and sample collection. A.I.C., A.M.A., A.d.l.G.P. and R.M.G. processed the samples. A.d.l.G.P. and A.M.A. conducted the data analysis and interpretation. A.d.l.G.P., A.M.A. and A.M.C. wrote the manuscript. All authors performed a critical review of the final manuscript.

**Funding:** This research was funded by the European Commission (DynaHEALTH-HORIZON 2020 GA No: 633595) and the Spanish Ministry of Economy and Competitiveness (BFU2012-40254-C03-02). Further support was obtained from, Spanish Ministry of Innovation and Science (Junta de Andalucía), Excellence Projects (P06-CTS-02341). ADLGP thanks the Mexican governmen<sup>t</sup> and the National Council on Science and Technology (CONACYT) for her PhD grant. The funders had no role in the study design, data collection, data analysis, decision to publish, or preparation of the manuscript.

**Acknowledgments:** The authors sincerely thank the women and children involved in the PREOBE study for their valuable participation. We are also grateful to personnel, scientists, staff and all people involved in the PREOBE team who have made this research possible. We acknowledge members of the Autonomous University of Barcelona for their assistance in statistical analysis. Members of the PREOBE team include: University of Granada. Spain: EURISTIKOS Excellence Centre for Paediatric Research. Department of Paediatrics: Cristina Campoy (PI), Luz Mª García-Valdés, Francisco J Torres-Espínola, Mª Teresa Segura, Cristina Martínez-Zaldívar, Tania Anjos, Antonio Jerez, Daniel Campos, Rosario Moreno-Torres, Mª José Aguilar, Iryna Rusanova, Jole Martino, Signe Altmäe; Department of Obstetrics and Gynecology: Jesús Florido, Carmen Padilla; Department of Biostatistics: Mª Teresa Miranda; Mind, Brain and Behavior International Research Centre: Andrés Catena, Miguel Pérez-García; Department of Legal Medicine: Jose A. Lorente, Juan C. Alvarez; Department of Pharmacology: Ahmad Agil; ICTAN-CSIC–Madrid. Spain: Ascensión Marcos, Esther Nova, Department of Nutrition and Bromatology. University of Barcelona. Spain: Mª Carmen <sup>L</sup>ópez-Sabater; Lorgen, S.L.: Carmen Entrala; Rowett Institute, University of Aberdeen, UK: Harry McArdle, University of Nöttingham, UK: Michael Symonds; Ludwig-Maximiliam University of Munich, Germany: Berthold Koletzko, Hans Demmelmair, Olaf Uhl; University of Graz, Austria: Gernot Desoye; Abbott Laboratories: Ricardo Rueda; University of Umeå, Sweden: Staffan K Berglund.

**Conflicts of Interest:** The authors declare no conflict of interest.
