Investigators propose this study in order to answer the following research question: An educational intervention and breastfeeding support at postpartum will increase the frequency and total breastfeeding duration in the intervention group? This is a randomized (with control and intervention groups) study, open and parallel (1: 1 ratio between study groups) with 200 pregnant women in the second or third trimester, according to their body mass index (BMI, kg / m2) with excess weight (BMI> 29 pre-pregnancy weight) and that will address their pregnancy in the public health services and hospitals belonging to the Health Ministry of 5 districts: Coyoacán, Magdalena Contreras, Tlalpan, Xochimilco and Alvaro Obregón in Mexico City.

The intervention group and the control group will have the same characteristics for eligibility.

The main phases to develop the study are PHASE 1. INTERVENTION DESIGN PHASE 2. IMPLEMENTATION OF THE INTERVENTION. PHASE 3. FOLLOW-UP The intervention will be offered at 3 times: 1) Educational intervention (a workshop) to pregnant obese women. The workshop will be held by an International Board Certified Lactation Consultant (IBCLC) to promote exclusive breastfeeding and to encourage a better breastfeeding performance in accordance with the WHO recommendations. The workshop will be held at convenient times and will be conducted for groups of 8 to 10 participants; 2) Immediate breastfeeding support at hospital by an IBCLC and; 3) The women will be exposed to early telephonic follow-up during the first week of their children´s lives and each month until six months of life. Then, if the breastfeeding continues, every two months until the first year of their children´s life.

At the first month postpartum, investigators will visit participants at home, both the control group and the intervention group, for collecting information on breastfeeding practices, for taking a breast milk sample to estimate its fatty acids content, and a blood sample (serum) to obtain the C-Reactive Protein. Also, the investigators will take anthropometric measurements of the children to evaluate their growth (weight, length, and skinfold thickness). Investigators will ask for breastfeeding practices and diet of the participants through a 24 hours recall.

The results of this intervention group will be compared with the control group: pregnant obese women without educational intervention or telephonic follow-up.

BACKGROUND Maternal obesity alters the composition of the breast milk beyond the influence of diet on it. Obesity delays copious production of breast milk (Lactogenesis stage II) and it concurs with the synthesis of prolactin (PRL), in response to the decreased sucking of the child.

Besides that, obese mothers have a higher risk of complications in the delivery; where it is common to experience great physiological stress and having a high probability of cesarean, which metabolically does not interfere with breastfeeding but delays its establishment. The excess of subcutaneous fat in the area of the areola of mothers with obesity cause discomfort and stress in the mother and crying in the infant, hindering the correct latch of the infant to the nipple, weakening the neurological stimulus that triggers Prolactin production.

Also, obese mothers have reported an increased feeling of insufficient milk, compared with non-obese mothers and, women with obesity report lower self-efficacy than their pairs without obesity.

Despite the implementation of educational interventions to promote the establishment of breastfeeding in obese women, the results have not been favorable to increase the prevalence of breastfeeding.

To help to improve this practice in women with obesity, it raises the following research question:

An intervention specifically designed to lessen the problems in establishing breastfeeding in women with obesity, which includes: an educational intervention with support during the pregnancy, the immediate postpartum period and the first year of life; increases the frequency of exclusive and predominant breastfeeding during the first month of life, and the total duration of breastfeeding?

METHODOLOGY PHASE 1 INTERVENTION DESIGN The intervention will be made with information derived from a focus group (FG). The main objective is to identify the barriers of a mother with obesity for breastfeeding and, to explore the ideas to overcome them. Investigators will develop a guide to lead the FG discussion.

The main characteristic of women participating in the FG is pregnant women with obesity, the distinction between primiparous and not primiparous women and those who have breastfed before at least for 6 months.

Workshop Design.

With an expert on learning techniques as a collaborator, investigators will design the workshop with the validated messages derived from the FG and it will be complemented by using the experience of an International Board Certified Lactation Consultant (IBCLC). The workshop will be divided into three stages:

• First stage: Basics of breastfeeding and its significance for the health of the baby and mother.
• Second stage: discussion of the problems that may arise, particularly in mothers with obesity. Recommendations and appropriate techniques to solve these problems will be given trough Games and communication activities will be driven.
• Third stage: Treatment of the most common problems and the counseling for solving them.

PHASE 2. IMPLEMENTATION OF THE INTERVENTION. Step 1. Enrollment. This stage is scheduled to take place within 5 months and it has two strategies: 1) with previous authorization of the Health Ministry of Mexico City, investigators will request information from the censuses of each health jurisdiction where there are all the pregnant women identified, or; 2) investigators will approach to pregnant women at the time they attend to their medical consultation.

Once investigators have identified the pregnant women, they will ask for the pregnant women informed consent (adult) / written assent (adolescent) to obtain information about them since the eligibility criteria will be evaluated.

Sociodemographic data and a self-efficacy on breastfeeding questionnaire will be collected. Then, investigators will assign randomly each one of the women to a study group (intervention group or control group).

Step 2. Basal phase. The assignment to a study group is the beginning of the intervention and it is considered as the baseline of the study.

<Activities for the Intervention group>

The intervention will be set at different times:

1. During pregnancy: The workshop. Also, there will be collected another self-efficacy questionnaire at the end.

2. At immediate postpartum: Investigators will identify the arrival of a woman of the study to any of the five hospitals selected for the study. For the intervention group, in addition to the collection of data of health conditions of the mother and her baby, one of the IBCLC will attend and provide immediate support for the establishment of breastfeeding within the first few hours old of the baby. The IBCLC may solve all doubts of the mothers; give support, supervise and guide the initiation of breastfeeding, explain the proper grip, suggest the ideal positions to breastfeeding for both the mother and the newborn, this support it is supposed to be intensive. All these activities must be coordinated with the physicians and nurses from each of the five hospitals in order to follow the rules and requirements that each hospital has established.

3. After delivery and until the first year of life of the children: the intervention will consist of two steps.

   1. During the first 7 days of the life of the infant. An IBCLC will call the mother daily.
   2. A telephonic follow-up at 2 weeks old of the baby and then, a phone call each month until reaching 6 months; then, every two months until the baby will have one year of life. With the calls, investigators pretend to collect information about the duration and type of feeding. There is the possibility that the support will be held via "Skype" if the women prefer it.

<Activities for both groups (intervention and control)> Investigators will deliver written relevant information about the recommended alimentation of the women at postpartum as well as some ideas for physical activity. This technical information is derived from the literature and will be expressed in a simple and accessible way.

PHASE 3. FOLLOW-UP At a month postpartum, investigators will visit participants at home, both the control group and the intervention group, for information on breastfeeding practices. Also from the mother, a breast milk sample will be taken to determine the composition of fatty acids of it, a blood sample to determine C-Reactive Protein and also investigators will collect dietary information. Additionally, weight, length, and skinfold thickness of the baby will be taken. The project staff will be standardized for newborn anthropometric measurement, following the technique of Lohman.

Sample size and statistical power Investigators will study 200 obese pregnant women, 100 per study group. This sample size was calculated to detect a difference in the prevalence of exclusive breastfeeding (at one month postpartum) in 10 percent (12 to 22%), with a statistical power of 90%, a level of significance >0.05, a nonresponse rate of 50% and 15% of abandonment postpartum. To achieve the sample size, recruitment will be held for 5 months, hoping to incorporate to the study, at least, two women daily. This calculation was performed using information on the number of women who could meet the inclusion criteria of the study.

To achieve this sample size, investigators estimated to screen a total of 3,700 women in the primary care level health services in order to identify women who meet the inclusion criteria as described above.

According to similar studies, to calculate the number of women needed to get 200 women (100 in each group) investigators did as it follows:

All pregnant women attending health centers n= 3,700 It is expected that at least 34% of women have a body mass index (BMI)> 29 n= 1,258 It is expected that 40% meet inclusion criteria n= 503 Only 50% agree to participate n= 251 Approximately 80% give birth in the reference hospital n= 200

Data management Study participants will be assigned a unique identification number. A subject identification list will be created, including the subjects identification number, personal information and contact information of each subject participating in the study. Only the main investigator will have access to this list in order to make it possible to trace and identify an individual subject. This list will also help to carry out medical auditing. For all the analysis and data management, the identification number will be used in order to ensure confidentiality and privacy of the subjects.

Once data is collected by fieldworkers, the completed questionnaires will be brought to the headquarters of the study, where supervisors will check for potential mistakes or missing information. Investigators will use a case report form per participant, where a checklist of all information to be collected from them and the quality of it, will be recorded. The case report form will be filled out by the field supervisor every time is checking the file of each subject. The purpose of the case report form will be for monitoring the quality of the information collected, and to check that all the information is being collected on time.

Data entry will be performed continuously during the course of the study. Data will be entered in duplicate for quality control. In case there are missing data or errors in data collection, the fieldworkers will go back to participants and recover the information when possible. Regular backup of databases procedures will be conducted.

Statistical processing and analysis

Descriptive statistics (summary measures, according to variable type and measurement scale) including means, medians, standard errors and variances for each of the stages of data collection (baseline and follow-up), as applicable. To analyze baseline differences between the study groups, comparisons between groups will be made by the difference of proportions test for categorical variables and t tests for continuous variables. The statistics tests will include design information, adjusting the standard errors and applying a continuity correction.

For the analysis of sociodemographic information, a cluster analysis will be used to identify groups of interest considering some characteristics of women.

Analytical or inferential statistics (test to be applied by type of variable: if necessary, statistical hypotheses and test procedures).

To evaluate the effect of the intervention data will be analyzed as panel data comparisons of means and variances. ANOVA, ANCOVA MANOVA and for comparing the groups: analysis of variance with and without intervention between and within groups.

To evaluate the relationship between obesity and breastfeeding performance investigators will use regression models were conducted and sociodemographic and anthropometric of each of the participants and their children will be included.

On the other hand, regression models will be conducted to analyze the relationship between the composition of breast milk and the infant's growth at one month and at 12 months.

All the analysis will be done with intent to treatment.

Qualitative analysis For the analysis of the educational intervention, qualitative analysis will be carried out through satisfaction surveys and open-ended questionnaires.

Inclusion Criteria:

• Pregnant Women <18 years old with a BMI >=28, and women <18 years old with a BMI >=27, utilizing their pre-pregnancy weight.
• Pregnant women within the second or early third trimester (week 20 through week 34 of gestation).

Exclusion Criteria:

• Pregnant women under 15 years old.
• Pregnant women diagnosed with HIV or AIDS, Hepatitis B and C, or the Human T lymphotropic virus. In the presence of these, women have the contraindication to feed their children with breast milk.
• Pregnant women with medical conditions that could interfere with breastfeeding, as severe infections transmitted through breast milk.
• Pregnant women with previous breast surgery (as breast reduction) because the lactiferous ducts end up damaged and may lead to poor or no milk production at all.
• Pregnant women that are taking medications that prevent carrying out breastfeeding.
• Pregnant women with a multiple pregnancy (in case of twins, the first born should be taken for the study).

Exit criteria:

• Newborns with less than 35 weeks of gestational age.
• Newborns dispatched to the neonatal intensive care unit (NICU) from the first day of life.
• Newborns who present major congenital malformations, severe enough to prevent the breastfeeding.

Elimination criteria:

• Newborns with hypertrophy (large for gestational age), because they may present hypoglycemia and therefore some should require to remain in fast even after starting oral feeding and especially on the first day of life.
• Newborns that enter to the Intermediate Care Unit for a neonatal or maternal adverse event even if the breastfeeding was already initiated.

The investigators do not plan to make IPD available