During the twelve months of the study, 2,929 women were delivered at the institution and 124 women were classified as severe maternal morbidity, according to the mixed set of criteria applied. Two maternal deaths and 81 fetal deaths occurred during the same period, resulting in a ratio of maternal death of 70.1 maternal deaths per 100,000 live births and a stillbirth rate of 27.6 per 1,000 deliveries. The rate of maternal death in severe morbidity was 1.6%, what means that the case/fatality ratio was 62:1.
The characteristics of the women classified as near miss were: mean age 27.5 (± 7.4) years (slightly more than 15% of the women were adolescents), 42 women were nulliparous and 32 had had three or more previous deliveries. Ninety-nine women were pregnant and the other 25 were admitted to the study during the puerperium. Mean gestational age at the time of inclusion to the study was 30.3 (± 6.9) weeks and 90% of the women in the puerperium were in the first week following delivery. When comparing with data from the general population attending the same maternity, the most marked differences of near miss cases were the earlier interruption of pregnancy and the higher rate of Caesarean section (Table ). Considering the two groups of cases of maternal morbidities (Mantel and Waterstone cases), no differences were observed (data not shown).
Characteristics of near miss cases and general obstetric population (GOP) attending the tertiary care Maternity
Four cases of near miss occurred due to miscarriage and three of those women were discharged from hospital in good condition prior to resolution of the gestation and were referred to their primary care center. One of these women became lost-to-follow-up and there is no data on the outcome of her pregnancy. Of a total of 118 deliveries, there were 21 vaginal deliveries (two requiring the use of forceps) and 97 Caesarian sections (82.2%). Mean gestational age at the time of resolution of the pregnancy was 33.1 (± 5.9) weeks.
Fifty-seven women (46%) had at least one significant morbid antecedent and the most frequent cause of morbidity was preeclampsia, which was present in 64 women (51.2%). The primary determinant factors of severe morbidity detected in this sample, as well as other general characteristics of the samples, are in Table . In more than half the cases, hypertensive syndromes were the primary determinant factor of near miss.
With reference to the criteria used to classify near miss, 62 women were initially included according to Mantel's proposal, while 86 were classified according to Waterstone's proposal. Twenty-four women presented criteria common to both authors at the moment of inclusion as a case of near miss. Of the six criteria proposed by Waterstone, all were used at least once in the present sample, while only 8 of the 19 criteria proposed by Mantel were used, as shown in Table . Severe preeclampsia and admission to the ICU were the main causes of near miss found in 45 and 40 women respectively. Other frequent causes were severe hemorrhage (13 women) and eclampsia (12 women).
During the hospital stay, 49 women initially classified by Waterstone's criteria were sent to ICU. At the hospital discharge, these women could also be classified as severe maternal morbidity according to Mantel criteria. The number of patients that anytime during their hospital stay would have qualified for any definition is 78. At any time during hospital stay, 112 women would fit the Mantel definition and 90 women would fit the Waterstone definition. The 34 women not incorporated by the Waterstone definition presented heart disease (15:34), respiratory complications (4:34), other non obstetric complications (13:34). They also included a case of ectopic pregnancy and a case of abruptio placentae that could not be classified by Waterstone as severe hemorrhage but has been managed in the ICU. Twelve women not incorporated by the Mantel definition presented severe preeclampsia.
Regarding the ICU utilization, a total of 112 women were admitted to the ICU, 35 of these for intensive clinical support and the others for monitoring and surveillance. However, only 40 women were initially included in the study because of the criterion "admission to ICU". The median duration of stay in the ICU was 3 days (range 1–50 days) and 15 women were submitted to invasive mechanical ventilation for at least one day, for a total of 67 days of artificial ventilation. Thirty-one women required a transfusion of blood-derivatives and used 144 units of packed red blood cells, 82 units of fresh frozen plasma, 36 units of concentrated platelets and 11 units of cryoprecipitate. Of this total, nine women received five or more units of packed red blood cells and were included in the study on the basis of the respective criterion established by Mantel, as shown in Table . A total of 45 women developed organ dysfunction and all of them had been admitted to the ICU.
The severe maternal morbidity ratio varied between 15 cases/1000 deliveries and 42 cases/1000 deliveries, according to the definitions used: mixed criteria – 42 cases per 1000 deliveries (124:2929), Mantel – 38/1000 deliveries (112:2929), Waterstone – 31/1000 deliveries (90:2929), ICU utilization – 38/1000 (112:2929) and organ dysfunction – 15/1000 deliveries (45:2929).
Forty-five women (36.3%) required special procedures and a total of 126 special procedures were performed, 102 of them in women admitted to the ICU for intensive support (80.9%). The most frequent procedures carried out were the installation of central venous access, echocardiograph and invasive artificial ventilation, as shown in Table . Although eight women were submitted to hysterectomy, in only four of them was this procedure the initial criteria for classification as near miss.
Special procedures carried out in the care of women with near miss
The mean total duration of hospital stay was 10.3 (± 13.24) days. Table shows the mean total duration of hospital stay and the number of procedures by subgroups of women classified according to the criteria proposed by Mantel or Waterstone, or according to admission to the ICU for whatever cause or for intensive support, compared to the rest of the sample. In general, the duration of hospital stay and the number of special procedures were significantly greater when Mantel's criteria or admission to the ICU for intensive support was used.
Total duration of hospital stay (in days) and number of special procedures in the care of women with near miss, by subgroups
Regarding maternal-fetal outcome, 116 women were discharged from hospital in conditions of good health, whereas 8 women were discharged with at least one sequela (8 cases of infertility because of hysterectomy and, in one of these women, poly neuromyopathy associated with sepsis. Two women were excluded from the analysis because they died. The first of these cases was a 21-year old pregnant woman, primigravida, who had cardiac insufficiency and severe pulmonary hypertension secondary to valvular cardiopathy (double mitral lesion, tricuspid and aortic). Approximately one week prior to her death, this pregnant woman's cardiac insufficiency became progressively worse. At 28 weeks of gestational age, she had been referred from another tertiary care hospital to the ICU, where maternal and fetal death occurred on the day of her admission following sudden accentuated hemodynamic deterioration. The second case of maternal death also occurred in a 21-year old woman who had had one previous delivery and who had been hospitalized one week earlier in a secondary hospital with jaundice during the 35th week of gestation. After four days of hospitalization, she was found to have premature placental abruption, and subsequent fetal death occurred. She then developed a coagulopathy and was referred to the ICU where she arrived with multiple organ dysfunction and died four days later. Both cases of maternal death, however, were initially identified as near miss according to Mantel's criteria of "admission to the ICU for whatever cause".
With respect to fetal outcome, 12 stillbirths occurred (five following vaginal delivery and seven following Caesarian section), resulting in a stillbirth rate four times higher than that observed in the hospital (112.1 stillbirths for every 1,000 deliveries).