here is an increase in obesity in developed countries, multifactorial in origin, which combines the lack of physical exercise, changes in diet composition and increased caloric intake. Although overweight is an increasingly important global health problem, the lack of motivation to face it more decisively in daily clinical practice is worrying.

The World Health Organization defines normal weight, overweight, obesity and morbid obesity as body mass index (BMI) of 18.5 to 24.9; 25 to 29.9; 30 to 39.9 and 40 or higher, respectively.

Spain is not an exception in this trend, but rather the opposite. Obesity in our country is reaching more worrying figures and comparative studies with other countries around place us at the forefront, with overall prevalence figures, both in children and adults, of around 25% (Finucane et al. 1980). According to the latest National Health Survey of Spain published in 2012, the main results highlight the continuous rise in obesity, affecting 17% of the adult population (INE 2013).

The prevalence of obesity in women of reproductive age and pregnant women varies widely depending on the definition, the year and the characteristics of the study population, but it has increased in line with an increased prevalence of obesity in the general population. This alarming increase has made that more than a fifth of the European women who become pregnant in developed countries enter the clinical category of obesity (WHO 2014; Basterra-Gortari et al. 2011).

Obesity in women can negatively affect the course of pregnancy, with complications for both the mother and the fetus. The main aim of our study is to evaluate obstetric complications and perinatal outcomes in patients with morbid obesity (BMI ? 40.0 kg/m²) controlled in the Obstetric Unit of Hospital Universitario Dr. Peset in Valencia, Spain.

Its secondary objective is to compare the results obtained in morbidly obese patients with a control group of pregnant women with normal weight (BMI 18.5-24.9 kg/m²) controlled in the same Hospital Unit.

This is an observational and retrospective casecontrol study in which obstetrical complications and perinatal outcomes in patients with morbid obesity (BMI ? 40.0 kg/m²) were evaluated and compared with those in patients with normal weight (BMI 18.5 to 24.9 kg/m²) in the time period between May 2008 and July 2016.

In the case group, patients with singleton pregnancies, controlled in our High Risk Obstetric Unit and who met the criteria for morbid obesity -defined as BMI ? 40 kg/m² according to the World H ealth Organization (WHO) -were included.

The control group was made of patients with singleton pregnancies and normal weight (BMI 18.5-24.9 kg/m²) controlled in the same Hospital Unit during the same period.

The maternal characteristics included and compared between two groups age, parity, BMI, pregestational diabetes and chronic hypertension. The analyzed maternal outcomes included preeclampsia, gestational diabetes, spontaneous onset of labour versus induced labour, mode of delivery, postpartum hemorrhage and venous thromboembolism. As neonatal outcomes, gestational age at birth, prematurity (defined as gestational age less than 37 weeks), weight at birth, Apgar score at one minute and five minutes after birth and umbilical cord blood pH were included.

The analysis of the data and the results were obtained by using the statistical software SPSS version 20 and Microsoft Excel 2007. For both groups descriptive statistics were used. The variables are expressed in percentages and means ± standard error. The statistical significance tests used were the Chisquare and Fisher's exact test for dichotomous qualitative variables and the Student t for continuous variables. For quantitative variables, multiple regression models were used. In all cases, statistically significant differences were considered when p <0.05.

The study was approved by the Ethics Committee for Ethics in Clinical Research of the hospital. Informed consent was obtained from all the participants and the confidentiality of all of them was maintained.

A total of 50 patients were included in both study groups.

The demographic characteristics of both groups are shown in Table 1. Within the group of morbidly obese patients, the mean age was 30.95 years and the mean BMI 43.36 kg/m² (40-58). In the group of patients with normal weight, the average age was 29.76 years (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41) and the average BMI 22.27 kg/m² (20-24.9). The morbidly obese patients had a higher rate of nulliparity (P = 0.03) and chronic hypertension (P = 0.008) than patients with normal weight. Neither statistically significant differences in the previous mode of delivery (caesarean section or vaginal) nor a history of pregestational diabetes were found.

Maternal outcomes were obtained by univariate analysis and are shown in Table 2. In the group of morbidly obese patients, higher rates of preeclampsia (P = 0.03), gestational diabetes (P = 0.013) and delivery by caesarean section (P = 0.04) were recorded compared to control patients with normal weight. There were no differences in the onset of labour and in the occurrence of postpartum venous thromboembolism between the two study groups. However, there were more cases of postpartum hemorrhage in obese patients than in the group of patients with normal weight (14% vs 4%), but this difference did not reach statistical significance. Perinatal outcomes of the study are shown in Table 3. In our study, no statistically significant differences in terms of perinatal outcomes were found compared to those obtained in the group of patients with normal weight. IV.

Overweight and obesity among pregnant women have recently become a worldwide problem.

Obesity during pregnancy is associated with many maternal and perinatal risks. The appearance of these risks is proportional to the degree of obesity presented by the patient (Torloni et al. 2009; Scott-Pillai et al. 2013; Blomberg et al. 2013). Managing these problems and potentially reduce their risks is currently a challenge for specialists in Obstetrics (Gunatilake et al.

In our review, morbidly obese patients (BMI ? 40.0 kg/m²) had higher nulliparity (40%) and chronic hypertension (20%) rates than control patients with normal weight. However no significant data regarding pregestational diabetes were found. These data are consistent with the study published by Crane et al (Crane et al. 2013), where pregnant women with extreme obesity (BMI ? 50 kg /m²) presented higher nulliparity (59.2%), chronic hypertension (7%) and pregestational diabetes (5.6%) rates than the control patients with normal weight.

According to our figures, from the total of our obese pregnant patients, 10 (20%) had preeclampsia, 12 (24%) gestational diabetes and 22 (44%) delivered by caesarean section. 4 (8%) out of the obese pregnant women who developed preeclampsia during pregnancy, suffered already from chronic hypertension at the beginning of the study. These data are similar to those obtained in other studies (Crane et al. 2013;Weisset al. 2004). According to the literature reviewed, pregnant women with obesity (BMI ? 30.0 kg/m² have a higher prevalence of gestational diabetes (Ehrenberg et al. 2002, Gross et al.1980), higher rates of hypertensive disorders of pregnancy (Robinson et al. 2005 We are aware of the limitations of our study. On the one hand, because of the retrospective nature of our research; on the other hand, because of the small sample size of the study group (N=50). This could explain the lack of statistical significance in most of the variables studied.

V.

Pregnant women with morbid obesity (BMI ? 40.0 kg/m²) present a higher risk of maternal and perinatal complications. Therefore, further development and the elaboration of programs from the preconception period are recommended. This should be done in specialized units that value individual needs and the risk factors of each patient in order to prevent, reduce properly handle the complications that may arise for both mother and fetus.