Macrosomia and Its Relationship with Preconception Body Mass Index in Tijuana, Mexico

Research Article

J Fam Med. 2020; 7(10): 1234.

Macrosomia and Its Relationship with Preconception Body Mass Index in Tijuana, Mexico

Banuelos-Cisneros M*, Bermudez-Villalpando VI, Antunez-Ruiz VC, Gonzalez-Montiel E, Rodriguez-Jimenez CB and Martinez-Carrasco BA

Department of Family Medicine, Family Medicine Unit #27 (IMSS), Baja California Delegation, Mexico

*Corresponding author: Banuelos-Cisneros Monica, Department of Family Medicine, Family Medicine Unit #27 (IMSS), Baja California Delegation, Mexico

Received: October 05, 2020; Accepted: December 02, 2020; Published: December 09, 2020


Background: Cases of Obese and overweight women at their childbearing age have exponentially increased over the last 30 years. These fluctuations in the body do increase the risks for the fetus and the mother during the pregnancy.

Aim: The purpose of this study is to determine the relationship between macrosomia and the preconception Body Mass Index (BMI) in a primary medical center in Tijuana, Mexico.

Design and Setting: Analytic cross-sectional study.

Methods: Patients with children born during 2019 that had recorded their weight and height on their medical records in addition to the weight of the new born were identified. In descriptive statistics we use frequencies and percentages for qualitative variables; for quantitative mean and standard deviation. The Chi-square test was used to establish the relationship between macrosomia and preconception BMI; logistic regression was used for multivariate analysis, a p <0.05 was considered statistically significant.

Results: there is association between macrosomia and preconception BMI. The most significant relationship was in the overweight and obesity categories (p= 0.006). Through logistic regression, it was possible to verify that the obesity category was the most important risk factor to explain newborn macrosomia (B 1.439, OR 4.2, 95% CI 1.5-11.2, p 0.004).

Conclusion: Obesity has a strong association with macrosomia; pre-pregnancy weight plays a key role determining birth weight.

Keywords: Macrosomia; Obesity; Pregnancy 


The nutritional status before and during pregnancy is a fundamental determinant for fetal growth and newborn weight [1] because the health before pregnancy is closely related to the outcome of this state. The BMI is a parameter that is used for the diagnosis of overweight and obesity with validity throughout the world, it is defined as the weight in kilograms divided by the height in meters squared (kg/m2); is classified according to the World Health Organization (WHO) as normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), obesity grade I (30-34.9 kg/m2), obesity grade II (35-39.9 kg/m2) and obesity grade III (≥40 kg/m2) [2].

Macrosomia refers to excessive intrauterine growth beyond a specific threshold regardless of gestational age. This condition is defined as a birth weight ≥ 4000 grams. The American College of Obstetricians and Gynecologists (ACOG) supports the use of 4500 gram threshold for the diagnosis of macrosomia because morbidity increases significantly beyond this weight. A variety of factors predispose the newborn to macrosomia, including pre-existing maternal diabetes, uncontrolled gestational diabetes, maternal obesity and excessive weight gain during gestation. The interaction of these risk factors is complex and varies according to the BMI before pregnancy, race and ethnicity [3].

Ai-Koyanagi et al (2013), analyzed data from 276,436 births in 363 institutions in 23 developing countries in Asia, Africa and Latin America, found that mothers with BMI ≥35 kg/m2 have a higher risk of macrosomia than those with BMI <30 kg/m2. The prevalence of macrosomia in developed countries has increased from 15% to 25% in the last three decades, mainly by the increase in obesity and maternal diabetes [4]. Overweight and obesity are a major problem among women of reproductive age in Latin America and the Caribbean, where it is estimated that 70% of women between 20-49 years of age are overweight or obese. The overall prevalence of large for gestational age newborns in Latin America and the Caribbean is 16.5%. The highest rate of this condition was reported in Mexico (21.9%) [5]. In Mexico, according to the National Health Survey (ENSANUT 2016), 70% (66.7% men and 71.9% women) of the Mexican adult population are overweight or obese [6]. The objective of the research was to determine the relationship between fetal macrosomia and the maternal preconceptional BMI in the family medicine unit #27 (FMU 27) in Tijuana, Mexico.

Material and Methods

Study Design and Population

An analytical cross-sectional study was carried out in Tijuana, Baja California, Mexico, between January and December 2019. The research was developed at FMU 27 of the Instituto Mexicano del Seguro Social (IMSS). Patients with live newborns during the mentioned time period and who also had a record of weight and height before pregnancy, as well as a record of the weight at birth of the newborn, were included. The sample size was determined according to the most recent prevalence of macrosomia according to the National Center for Health Statistics [7]. Based on the local consultation network, patients with a diagnosis of Normal Pregnancy were identified according to the International Classification of Diseases (ICD-10). Subsequently, the medical records of the mothers and their children were investigated in the Family Medicine Information System (SIMF).


The collection of variables was done with a standardized data form; the variables collected were the following: maternal age, maternal risk age (pregnancy before 20 years or after 35 years), education, occupation, preconception BMI, and gestational diabetes Mellitus. The weight of the newborns was classified as macrosomia (≥4,000 g), normal weight (≥2500-3999 g), underweight (≥1500 <2500 g) and the degree of macrosomia was classified according to the ACOG, which includes the following categories: grade 1 (4000-4499 g), grade 2 (4500-4999 g) and grade 3 (≥5000 g).

Statistical Analysis

For the measurement of quantitative variables, mean and standard deviation were used, frequencies and percentages for qualitative variables. To establish a relationship between macrosomia and preconception BMI, the Chi Square test was performed. A logistic regression model was applied, macrosomia as the dependent variable and the maternal variables as independent. Statistically significant differences were considered with p values <0.05. Statistical analysis was processed with IBM SPSS version 21 software.


The study was approved by the Local Committee for Ethics and Health Research #204; with registration number R-2020-204-005. The research was carried out under the guidelines of the General Health Law on Health Research, the Declaration of Helsinki and Bioethical principles.


The total population was 164 patients; the minimum age was 18 years and the maximum 43, with a mean of 26.49. 82.9% (n= 136) had a non-risk age between 20 to 35 years, only 17.1% (n= 28) had ages of higher maternal risk. In schooling, the majority had secondary and high school studies with 39% and 39.6% respectively (Table 1). In occupation 75.6% (n= 124) were workers. In the preconception BMI (Figure 1), the underweight category had 2.4% (n= 4), normal weight 33.5% (n= 55), overweight 36.6% (n= 60) and obesity 27.4% (n= 45). The newborn's weight obtained the following frequencies: low weight 2.4% (n= 4), normal weight 67.7% (n= 111) and macrosomia 29.9% (n= 49). The most frequent degree of macrosomia (Figure 2) was grade 1 with 25% (n= 41), 4.3% (n= 7) grade 2 and 0.6% (n= 1) grade 3; 70.1% (n = 115) of the newborns did not have macrosomia.