Risk of recurrent adverse neonatal outcomes
While the rate of LGA or SGA was not different in index versus
subsequent pregnancies as a group, the risk of these complications in
their subsequent pregnancy was greatly increased in those women who had
LGA or SGA in their index pregnancy compared to those who did not
(Figure 1). For example, while the rate of LGA was similar in index and
subsequent pregnancies (16.7% vs 15.8%, p=NS), the rate of LGA in the
subsequent pregnancy was 45.1% in those women who had LGA in their
index pregnancy, with a RR of 4.55 compared to women who did not.
Likewise, while the rate of SGA was similar in index and subsequent
pregnancies (7.8% vs 8.7%, p=NS), the rate of SGA in the subsequent
pregnancy was 33.3% in women who had SGA in their index pregnancy, with
a RR of 5.01 compared to women who did not (Figure 1). This greatly
increased risk was also the case for the composite ANO
(death/dystocia/LGA/SGA) (Table 2).
Conversely, having an SGA baby in the index GDM pregnancy was associated
with a below average rate of LGA (6.1%, n=2/33), and having prior LGA
was associated with an SGA rate of only 1.4% (n=1/71) in the subsequent
GDM pregnancy. Women with no LGA or SGA history had a 7.8% rate of SGA
and 10.3% rate of LGA in their subsequent GDM pregnancy (Table 2).
Factors associated with ANO in the subsequent GDM
pregnancy
On univariate analysis, women with LGA in their subsequent GDM pregnancy
were slightly younger with higher parity compared to those without LGA.
They had a 17.5 kg greater median booking-in weight (84.5 (69.0-105.0)
vs 67.0 (58.0-82.0) kg, p<0.001), higher booking-in BMI (31.3
(26.9- 37.4)) vs 26.5 (23.1-32.0) kg/m2,
p<0.001) and a 2.5 kg greater interpregnancy weight gain than
women without LGA (4.7±8.4 vs 2.2 ±5.4 kg, p=0.002), despite a similar
interpregnancy interval. They had a higher fasting and two-hour glucose
on the diagnostic GTT. 47.8% had LGA in their index pregnancy, whereas
only 10.9% of women without LGA in the subsequent pregnancy had LGA in
the index pregnancy (p<0.001) (Table 3).
On univariate analysis, women with SGA in their subsequent GDM pregnancy
had a longer interpregnancy interval (3.9±2.1 vs 2.8±1.5 years,
p<0.001) compared to women without SGA. 70.3% had SGA in
their index pregnancy, versus 5.7% of women without SGA in their
subsequent pregnancy (p<0.001). There was a trend to lower
booking-in weight (65.0 (56.0-77.5) vs 71.0 (59.3-88.0) kg, p=0.07) but
no differences in booking-in BMI or interpregnancy weight change (Table
3).
On univariate analysis, women who had the composite ANO in the
subsequent GDM pregnancy had a higher parity compared to those who did
not. They had a 19.5 kg greater booking-in weight, higher booking-in BMI
(29.7 (24.9-35.4) vs 26.6 (23.1-32.1) kg/m-2, p=0.001)
and a 1.7 kg greater weight gain (p=0.01) between pregnancies. These
women had a higher fasting and 2-hour glucose on the diagnostic GTT.
43.5% had the composite ANO in their index pregnancy, compared to
21.2% of those without any ANO in their subsequent pregnancy
(p<0.001) (Table 3).
Based on results of univariate analysis, potential predictors of LGA in
the subsequent pregnancy were included in a binomial regression model
(prior LGA, BMI at booking-in, interpregnancy weight gain, and fasting
glucose at diagnostic OGTT). After backward stepwise removal, LGA in the
index pregnancy remained the strongest predictor of subsequent LGA, with
a RR of 3.13 (95%CI:2.20, 4.47, p<0.001) compared to women
without prior LGA. Booking-in BMI showed a modest association with LGA
outcome- RR 1.04 (95%CI:1.02, 1.07, p<0.001).
For the outcome of SGA in the subsequent pregnancy, prior SGA,
interpregnancy interval and booking-in weight were included in the
model. After adjustment, the RR of SGA in women with SGA in the index
pregnancy was 4.71 (95%CI:2.66, 8.36, p<0.001). For every
one-year increase in the interpregnancy interval, the RR of SGA was 1.51
(95%CI:1.19, 1.91, p<0.001)
For the composite ANO, the regression model included prior composite
ANO, booking-in BMI, interpregnancy weight gain, fasting glucose at
diagnostic OGTT and Europid/non-Europid ethnicity. After adjustment, the
RR of ANO was 2.01 (95%CI:1.46, 2.78, p<0.001) in women with
a prior history of ANO in the index pregnancy.