[The trend in pregnancies terminated by a cesarean operation in Mexico during 1991-1995]

In the last decades has been a worldwide trend to increase the number of cesarean sections as an alternative of obstetric resolution, phenomenon for which it was proposed a variety of explanation, this fact remains practically unknown in the institutions of the National Health System (NHS) in Mexico. To identify the trend of the pregnancy to end for cesarean sections during the years of 1991-1995 in the 32 states of de country, as well as of all the institutions of the National Health System. Descriptive, cross sectional and retrospective. We use the data of the Bureau of Statistics and Informatics of de Health Ministry of each one of the 32 states of the country, of the years 1991 to 1995, and of the number of cesarean sections made in the hospitals of the different institutions of the NHS. We started off with a data-base, to calculate frequency tables, and the specific rate of the cesarean section for each year, for each one of the states and institutions of the NHS. We calculate the secular trends using the annual rates of cesarean section, for each one of the states and institutions of the NHS. We also made bivariate analysis and estimated the odds ratio (OR) and 95% Confidence Interval (95% IC); and the statistic X2 for trend, setting the two tailed statistic significance level of 0.05. During the study period, there was 7,503,817 births in all hospitals of the NHS, of these births 1,929,865 (25.72%) was resolved by cesarean section. For the whole period it there was a clear trend to increment of the cesarean section, the rate for 1991 was 20.44%, and by 1995 was 28.58%, the raise for the period was 39.82%, with values of the OR for trend of 1.56; 95% IC (1.55-1.57). "P" < 0.05. The rate for institutions attending open population had an increment of 35.08% [OR trend 1.45; 95% IC (1.43-1.46), "p" < 0.05], of them the highest rate was for the State System of Health in 1995 with 29.78%, the rates for the remaining institutions varied from 16.57% for the IMSS/SOLIDARIDAD and 21.7% for the Health Ministry, all trends were statistically significant. In relation to the institutes attending closed population the raise was of 53.27% [OR trend 1.82; 95% IC (1.81-1.83), "p" < 0.05], with the highest rate for the National Defense Ministry which had a rate of 51-15%, the rates for the remaining institutions varied from 33.52% for the Mexican Institute of Social Security (IMSS) to 43.89% for the Institute of Safety and Social Services for the State Workers (ISSSTE), with exception of the Management of the Medical Services of the Mexican Oils (PEMEX) and the Marine Ministry (SECMAR), all trends were statistically significant. When the analysis of the cesarean section rates for the 32 states of the Mexican Republic was carried out, we found that in 1995, the national average rate was 28.58%, the lowest rate corresponded to the state of Zacatecas with 19.82% and the highest to the state of Nuevo León with 42.14%. There was a tendency to increment for all states which varied from 23.55% for the state Chiapas and 67.97% for the states of Querétaro, all increments were statistically significant. We conclude, that rates of cesarean section for both, institutions of NHS and states of the Mexican Republic, are of the highest in the world, no matter what big the interinstitutional and interstate variation are. The highest rates occurred in institutions attending closed population, and the states with a higher degree of socioeconomic development.