Association between interpregnancy interval and hypertensive disorders of pregnancy: Effect modification by maternal age

Associations between the time interval from myomectomy to subsequent pregnancy and the obstetric outcomes: A population-based cohort study

OBJECTIVE

To investigate the associations between time interval from myomectomy to pregnancy (TIMP) and subsequent pregnancy and obstetric complications, and to explore whether these associations vary according to maternal age at birth.

METHODS

A retrospective population-based cohort study was conducted from 2008 to 2017. Data were extracted from the National Health Insurance Research Database and the Taiwan Maternal and Child Health Database, comprising 2024 379 births from 1 391 856 pregnancies. Eligible cases were identified using diagnostic and procedure codes; 4006 first singleton births in 4006 women after their first laparotomic myomectomy were identified. We estimated the risks of pregnancy and obstetric outcomes according to TIMP (<6, 6-11, and ≥12 months). Subgroup analysis was performed by further dividing according to maternal age at birth (18-34 vs ≥35 years old).

RESULTS

We observed higher risks of gestational hypertensive disorders (adjusted odds ratio [aOR] 1.97, 95% confidence interval [CI] 1.22-3.18, P = 0.005) and neonatal death (aOR 4.59, 95% CI 1.49-14.18, P = 0.008) for TIMP of <6 months versus TIMP of 6-11 months. Likewise, a TIMP ≥12 months was associated with increased risks of gestational hypertensive disorders (aOR 1.72, 95% CI 1.14-2.58, P = 0.010), and neonatal death (aOR 3.27, 95% CI 1.16-9.24, P = 0.025) versus a TIMP of 6-11 months. In subgroup analysis, women over 35 years old still had higher risks of gestational hypertensive disorders when TIMP was <6 months (aOR 2.26, 95% CI 1.17-4.37, P = 0.015) or ≥12 months (aOR 2.04, 95% CI 1.17-3.54, P = 0.012), and a higher risk of neonatal death when TIMP was <6 months (aOR 4.05, 95% CI 1.06-15.53, P = 0.041); whereas women aged 18-34 years old did not.

CONCLUSIONS

This study suggests that a TIMP between 6 and 11 months is associated with lower risks of gestational hypertensive disorders and neonatal death compared with a TIMP <6 months or ≥12 months, especially for women over 35 years old.

Interpregnancy interval and adverse birth outcomes: a population-based cohort study of twins

BACKGROUND

To investigate associations between interpregnancy intervals (IPIs) and adverse birth outcomes in twin pregnancies.

METHODS

This retrospective cohort study of 9,867 twin pregnancies in Western Australia from 1980-2015. Relative Risks (RRs) were estimated for the interval prior to the pregnancy (IPI) as the exposure and after the pregnancy as a negative control exposure for preterm birth (< 37 weeks), early preterm birth (< 34 weeks), small for gestational age (SGA: < 10th percentile of birth weight by sex and gestational age) and low birth weight (LBW: birthweight < 2,500 g).

RESULTS

Relative to IPIs of 18-23 months, IPIs of < 6 months were associated with a higher risk of early preterm birth (aRR 1.41, 95% CI 1.08-1.83) and LBW for at least one twin (aRR 1.16, 95% CI 1.06-1.28). IPIs of 6-11 months were associated with a higher risk of SGA (aRR 1.24, 95% CI 1.01-1.54) and LBW for at least one twin (aRR 1.09, 95% CI 1.01-1.19). IPIs of 60-119 months and ≥ 120 months were associated with an increased risk of preterm birth (RR 1.12, 95% CI 1.03-1.22; and (aRR 1.25, 95% CI 1.10-1.41, respectively), and LBW for at least one twin (aRR 1.17, 95% CI 1.08-1.28; and aRR 1.20, 95% CI 1.05-1.36, respectively). IPIs of ≥ 120 months were also associated with an increased risk of early preterm birth (aRR 1.42, 95% CI 1.01-2.00). After negative control analysis, IPIs ≥ 120 months remained associated with early preterm birth and LBW.

CONCLUSION

Evidence for adverse associations with twin birth outcomes was strongest for long IPIs.