After combination laser conization, 62 patients had 75 pregnancies progress
ing beyond 27 weeks of gestation and were compared with 150 pregnancies in
control subjects matched for age and parity. The mean birthweight was signi
ficantly lower in patients than in control subjects. This difference was du
e to a higher frequency of premature birth, The premature birth rate was 18
.7% after conization, compared with 6.7% in control subjects, There was no
difference in the occurrence of preterm premature rupture of the membranes
in the two groups. Smoking had a significant influence on the outcome of pr
egnancy in both univariate and multivariate analysis, and in both patients
and control subjects, Multivariate analysis demonstrated both conization an
d smoking to be significant factors related to the risk of premature birth.
The height of cone biopsy was also correlated with the risk of premature b
irth. The risk of preterm delivery was significantly higher when cone heigh
t was >20 mm, A strong correlation between increasing cone height and risk
of preterm delivery was demonstrated. Combination laser conization was asso
ciated with an increased risk of preterm delivery, but the cofactor smoking
was also significant, No other adverse effect of conization on the outcome
of pregnancy was observed.