The association between the multiple birth and breast cancer incidence: an update of a systematic review and meta-analysis from 1983 to 2022

BACKGROUND

It has been assumed that perinatal factors such as multiple pregnancies may affect subsequent breast cancer risk in the mother. Considering the inconsistencies in the results of case-control and cohort studies published in the world, this meta-analysis was conducted in order to determine the exact association between multiple pregnancies (twins or more) and the breast cancer incidence.

METHODS

This study was performed as a meta-analysis based on PRISMA guidelines by searching the international databases of PubMed (Medline), Scopus, and Web of Science as well as by screening selected articles based on their subject, abstract and full text. The search time was from January 1983 to November 2022. Then the NOS checklist was used to evaluate the quality of the final selected articles. The indicators considered for the meta-analysis included the odds ratio (OR) and the risk ratio (RR) along with the confidence interval reported in the selected primary studies. The desired analyzes were performed with STATA software version 17 to be reported.

RESULTS

In this meta-analysis, 19 studies were finally selected for analysis, which fully met the inclusion criteria. Of these, 11 were case-control studies and 8 were cohort ones. Their sample size was 263,956 women (48,696 with breast cancer and 215,260 healthy) and 1,658,378 (63,328 twin or multiple pregnancies and 1,595,050 singleton pregnancies), respectively. After combining the results of cohort and case-control studies, the effect of multiple pregnancies on the breast cancer incidence was equal to 1.01 (95% CI: 0.89-1.14; I2: 44.88%, P: 0.06) and 0.89 (95% CI: 0.83-0.95; I2: 41.73%, P: 0.07), respectively.

CONCLUSION

The present meta-analysis results showed, in general, multiple pregnancies were one of the preventive factors of breast cancer.

Twin birth: The maternal experience

OBJECTIVE

Twin birth is a special setting for women giving birth, and the experience of childbirth can be different from singleton birth. The objective of this study was to evaluate and compare the childbirth experiences of twin mothers and singleton mothers. We also aimed to identify the risk factors of a negative childbirth experience in the whole study population.

METHODS

All live diamniotic twin deliveries in the study hospital of at least 35⁺⁰ weeks of gestation with a plan of vaginal birth were included in this matched groups study from August 2015 to August 2019. For every twin birth, two singleton birth controls were selected and matched with parity, the actual mode of birth, and gestational weeks at birth. Six weeks after birth, a Childbirth Experience Questionnaire (CEQ) was sent to mothers, and 72 twin mothers and 126 singleton mothers returned the questionnaire.

RESULTS

The twin mothers' overall childbirth experience was positive. They reported a significantly lower opportunity to choose the birthing position (p < 0.001). Otherwise, there were no differences in the CEQ mean total scores between the study groups. Intrapartum cesarean section raised the risk of a negative childbirth experience and there was a high level of satisfaction with midwifery care among the whole study population.

CONCLUSION

The overall maternal experience in planned vaginal twin birth was positive. Twin mothers felt less often able to choose their birthing position, otherwise the childbirth experience did not differ from that of singleton mothers.

Mode of delivery, perinatal outcome and neurodevelopment in uncomplicated monochorionic diamniotic twins: a single-center retrospective cohort study

BACKGROUND

There is no agreement on the effect of planned mode of delivery in the perinatal morbidity and neurodevelopment in uncomplicated monochorionic diamniotic as well as regarding the safest mode of delivery. In this paper we have aimed to analyze the impact of the mode of delivery in uncomplicated monochorionic diamniotic twins ≥ 32 weeks of gestation.

MATERIAL AND METHODS

This study included 72 women, followed and attended at our department, with uncomplicated monochorionic diamniotic pregnancies who had a birth between 32.0 and 37.6 weeks of gestation from January 2012 to December 2018. Outcomes were recorded in women who underwent planned vaginal delivery (induced or spontaneous onset of labor), and women who underwent a planned cesarean section for any reason that excluded vaginal delivery. Primary outcomes included: (1) A composite of any of the following: neonatal death, 5-min Apgar score < 4, respiratory distress syndrome, bronchopulmonary dysplasia, sepsis, periventricular leukomalacia, intraventricular hemorrhage, and necrotizing enterocolitis. (2) Neurodevelopmental status at 2 years of corrected age.

RESULTS

In this period, 42 women (58.3%) had a planned vaginal delivery, and 30 women (41.7%) had a planned cesarean section. In the first group, 64.3% had a vaginal delivery. The rate of successful vaginal delivery was similar regardless the onset of labor. We did not find a higher composite perinatal morbidity in the planned vaginal delivery group (planned vaginal delivery: 3.6% vs. planned cesarean section: 8.3%, aOR 1.36, 95% CI 0.24-7.81). Considering the onset of labor, it was more frequent in the spontaneous subgroup (8.3% vs. 0%). The rate of neurodevelopmental impairment was higher in the planned cesarean section group, without reaching statistical significance [10.2% vs. 4.9%, aOR 1.53 (95% CI 0.37-6.29)].

CONCLUSIONS

In uncomplicated monochorionic diamniotic twins at ≥ 32 weeks of gestation, when the first twin is in vertex presentation, our results suggest that planned vaginal delivery is safe, with a successful outcome as well as high vaginal delivery rate.

Term twin birth - impact of mode of delivery on outcome

INTRODUCTION

The main aims of this study were to compare maternal and neonatal outcomes in term twin birth according to the planned mode of delivery and to study the effects of chorionicity and inter-twin delivery time on neonatal outcome.

MATERIAL AND METHODS

A single-center cohort study of 495 women with twin deliveries at ≥37⁺⁰ weeks of gestation. Term twin deliveries were divided into a trial of labor group (TOL, 69.3%) and a planned cesarean section (CS) group (30.7%). The primary outcomes were maternal and neonatal morbidity.

RESULTS

80.8% of women attempting TOL achieved vaginal birth. In the TOL group, mothers had less bleeding [median 500 mL (range 150-2700 mL) vs. 950 mL (range 150-3500 mL), p < 0.001) and fewer surgical complications (3.2% vs. 8.6%, p = 0.011), whereas second twins more often had five-minute Apgar scores of <7 (5.0% vs. 0%, p = 0.002) or umbilical artery pH < 7.05 (5.7% vs. 0%, p = 0.003), compared with the planned CS group. There was a slight, non-significant tendency for more NICU admissions in the TOL group, yet the need for NICU treatment was infrequent in the whole study material. Outcomes among dichorionic (DC) second twins were similar to those in the whole material, but among monochorionic (MC) second twins there were no differences between the TOL and planned CS groups. In secondary analysis, a five-minute Apgar score <7 occurred significantly more often in the DC group among second twins if the inter-twin delivery time exceeded 30 min.

CONCLUSIONS

TOL is a good option for women with twin pregnancy at term, regardless of chorionicity. Active management of labor for the second twin is important, also in DC births. Maternal outcomes were more favorable with TOL and although low Apgar scores and low umbilical blood pH may be more frequent after TOL - especially with the second twin - serious neonatal morbidity is rare and does not differ from that after planned CS.