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Table 5 Unadjusted and adjusted associations between gestational weight gain and maternal outcomes

From: Examining the provisional guidelines for weight gain in twin pregnancies: a retrospective cohort study

 

Below IOM GWG a

Above IOM GWG a

Maternal Outcome

Unadjusted Analyses

Adjusted Analyses b

Unadjusted Analyses

Adjusted Analyses b

 

OR (95% CI)

OR (95% CI)

OR (95% CI)

OR (95% CI)

Gestational age at delivery, weeks c

−0.28 (−0.66, 0.10)

−0.34 (−0.76, 0.07)

−0.10 (−0.47, 0.27)

0.01 (−0.39, 0.41)

PTB <37 weeks

 Overall

1.34 (0.94, 1.91)

1.28 (0.86, 1.93)

1.19 (0.84, 1.68)

1.09 (0.73, 1.62)

 Spontaneous

1.22 (0.80, 1.85)

1.16 (0.71, 1.90)

0.81 (0.53, 1.26)

0.78 (0.47, 1.30)

 Indicated

1.23 (0.82, 1.84)

1.20 (0.76, 1.91)

1.46 (0.99, 2.15)

1.34 (0.86, 2.09)

Labour induction

1.36 (0.93, 2.00)

1.54 (0.99, 2.39)

1.62 (1.12, 2.34)

1.65 (1.08, 2.53)

Mode of delivery

 Vaginal birth (unassisted)

1.48 (1.04, 2.12)

1.47 (0.96, 2.25)

0.91 (0.64, 1.30)

1.03 (0.67, 1.56)

 Forceps/ vacuum

0.75 (0.37, 1.53)

0.91 (0.40, 2.09)

0.74 (0.37, 1.48)

0.73 (0.32, 1.67)

 Caesarean section

0.73 (0.51, 1.04)

0.71 (0.46, 1.08)

1.18 (0.84, 1.67)

1.07 (0.71, 1.61)

Postpartum haemorrhage

1.08 (0.70, 1.67)

1.10 (0.67, 1.81)

0.99 (0.64, 1.53)

1.01 (0.62, 1.63)

Length of stay, days c

−0.30 (−0.60, −0.01)

−0.35 (−0.68, −0.02)

0.03 (−0.25, 0.32)

−0.04 (−0.36, 0.28)

  1. Abbreviations: BMI, body mass index; CI; confidence interval; GWG, gestational weight gain; IOM, Institute of Medicine; IQR, inter-quartile range; N, number; OR, odds ratio; PTB, preterm birth
  2. a Gestational weight gain categories (below, within, and above IOM GWG) are based on the 2nd and 3rd trimester weekly rates of GWG; GWG within the IOM GWG is the referent group for all analyses
  3. b All outcomes were adjusted for the a priori defined confounders, including maternal age, neighborhood-level income, maternal pre-pregnancy BMI, parity, smoking status, and chorionicity. Analyses were also adjusted for the baseline characteristics significant with a p-value < 0.2, including marital status. Despite having a p-value <0.2, pre-existing diabetes mellitus and attending prenatal classes were not included in the adjusted models, due to low frequency of occurrence in the three categories of GWG (pre-existing diabetes mellitus), or collinearity with other variables in the model (attending prenatal classes)
  4. c The corresponding effect estimates are a mean difference (95% CI), instead of OR (95% CI)