A multiple birth in the study experienced 2.91 times greater mortality compared to single births, similar to findings from other studies (13, 33).
This paper uses a large database of multiple birth cohorts to study relationships between air pollution exposure and non-infant children's respiratory health outcomes.
In general, women of very advanced maternal age are considerably more likely to have multiple births, and in this study, multiple birth rates were approximately 6% for the study group, which is three fold the rate reported among younger women.
In this study, multiple births have been studied, with particular reference to the twin births occurring in the Gemelli hospital, Rome.
However, the association between multiple birth and ASD in this study was weak and not statistically significant (Table 3, unadjusted odds ratio), whereas assisted reproduction technologies are strongly associated with multiple birth (23).
They are both added to the multiple birth group in this table The study medication was reported having been taken by 290/299 = 97 · 0 % of mothers who gave birth at home and by 107/401 = 26·7%7 % of those who delivered in facilities (overall 56·7%7 %, Table 2).
Of the 2006 women who were enrolled for the PIN3 Study, 37 had multiple birth or lost pregnancy, 159 requested to drop out or no future contact, 84 did not complete the first PIN3 interview, 87 did not deliver at UNC Hospitals or moved out of the area, 8 had medical problems at delivery, and 462 delivered before the Postpartum Study began.
Inclusion of singleton versus multiple births varied across studies.
Women with a known multiple gestation pregnancy or who had a multiple birth were excluded at enrolment or during the study.
For women with multiple birth experiences, the last birth experience was analysed in this study.
