Short Interpregnancy Interval: Risk of Uterine Rupture and Complications of Vaginal Birth After Cesarean Delivery

Abstract

A lthough the association between interpregnancy interval and the risk of adverse fetal and neonatal outcomes has been examined for vaginal delivery, the effects of birth interval on the safety and efficacy of vaginal birth after cesarean delivery (VBAC) are less well known. This study examined whether a short or long interpregnancy interval is associated with a risk of increased uterine rupture and other maternal morbidities in women attempting a VBAC.The database for the study involved a secondary analysis of a multicenter, record-based, retrospective cohort study of pregnant women with at least one prior cesarean that involved teaching university and community hospitals and nonteaching community hospitals. The cohort included 25,005 patients who delivered between 1995 and 2000 at 17 participating hospitals in the Northeastern United States. This subanalysis taken from that database included only women who decided to try a VBAC. Short interpregnancy interval cut-off points were <6, <12, and <18 months between prior delivery and conception dates; the long interval cut-off was Z60 months. The primary outcome of uterine rupture was defined as a uterine scar separation determined at laparotomy that was preceded by a nonreassuring fetal heart rate pattern, maternal signs or symptoms of acute blood loss, or hemoperitoneum to distinguish it from asymptomatic uterine dehiscence. Secondary outcomes were composites of maternal major morbidity and maternal requirements for blood transfusions.Of the 25,005 women with prior cesarean sections, 55% attempted a VBAC (n = 13,706). Data on the interval between cesarean sections was not available in 375, leaving 13,331 records available for analysis. The rates of short interpregnancy interval for <6 months, 6 to 11 months, and 12 to 17 months were 2.2% (n = 286), 8.3% (n = 1109), and 13.1% (n = 1741); that for the long interval was 19.7% (n = 2631). Uterine rupture occurred in 128 cases, for a rupture rate of 0.9% in those who attempted VBAC. Women with an interval of <6 months had a significant increase in uterine rupture rate, with an absolute risk of 2.7%, nearly a 3-fold increase relative to those with birth intervals >6 months. This short-interval group also had a significant 2-fold increase in the composite morbidity rate (absolute risk of 4.2%) and a 3-fold risk of receiving a blood transfusion compared with the women in the other interval groups. These increases in risk persisted when the data were adjusted for relevant confounders such as number of prior cesarean and vaginal deliveries, delivery gestational age, cigarette use, whether labor was induced, and maternal age, race, and parity. When the short interval cutoffs of <12 months and <18 months were used, the risks of uterine rupture, composite morbidity, and blood transfusion were not statistically different from the long interval group. The long interval was not an independent risk factor for any of the three outcomes. The overall failure to achieve a VBAC was about 23% among all patients and did not vary significa...

Study of cases of rupture uterus in a tertiary institute and its maternal and perinatal outcome

“…7 Most common site of rupture was lower uterine segment (37) and its extension most commonly on left lateral wall seen in 29 out of 46 cases, Similar observation was found in other studies. 73 and least common site was fundal rupture seen in 2 cases.…”

Severe maternal and perinatal outcomes from uterine rupture among women at term with a trial of labor

“…In addition, several studies have identified short interdelivery intervals of <6, 18 or 24 months as risk factors for UR. [16][17][18] In this study, women with interdelivery intervals of p18 months had a 60% increased risk of a severe outcome related to UR. This information may provide obstetric providers with even more motivation to counsel women who have had a cesarean to postpone a subsequent pregnancy for more than 1 year.…”

Prediction of scar integrity and vaginal birth after caesarean delivery

“…In retrospective studies, the rate of uterine rupture during a trial of labour after caesarean delivery is around 1% [3][4][5][6][7][8][9][10]. These studies seem to have included only symptomatic uterine rupture.…”

“…The following factors have been examined with regard to their ability to predict uterine rupture during a trial of labour after caesarean delivery: gestational age [4,19], maternal age [15], interdelivery interval [5,16], interpregnancy interval [7], suture technique for closing the hysterotomy [31], birth weight [18,24], previous vaginal delivery [3,6,21], induction of labour [10,28], ethnicity [22], pre-eclampsia or gestational hypertension [20], twin pregnancy [23], labour progress [27], and number of epidural doses [29]. A statistically significant association with uterine rupture was found in more than one study for the following variables: interdelivery or interpregnancy interval (higher risk with short interval, short interdelivery interval being defined as < 24months [16] or < 18 months [5], and short interpregnancy interval as < 6 months [7]), birthweight (higher risk if > 4000g) [18,24], induction of labour (higher risk) [10,32], oxytocin dose (higher risk with higher doses) [8,30], and previous vaginal delivery (lower risk of rupture if the woman ever delivered vaginally) [3,6]. In addition, a systematic review including 12 studies, showed that locked single layer closure of the caesarean hysterorotomy increased the risk of uterine rupture compared with double layer closure [31].…”