Fetal growth in pregnancies conceived after gastric bypass surgery in relation to surgery-to-conception interval:a Danish national cohort study

OBJECTIVE: To describe early and late fetal growth in pregnancies conceived after gastric bypass surgery in relation to time from surgery to conception of pregnancy. METHODS: National cohort study on 387 Danish women, who had laparoscopic or open gastric bypass surgery prior to a singleton pregnancy in which first trimester screening was performed between January 2008 and June 2011. Data were derived from national registers (Danish National Registry of Patients and Danish National Birth Registry, Pregnancy Complications and Abortion-clinical quality database (PreCAb) and the Danish Fetal Medicine Database). Main outcome measures were early and late fetal growth in relation to time from bariatric surgery to conception of the pregnancy. Early fetal growth was expressed as "Fetal Growth Index": the ratio between the estimated number of days from first trimester ultrasound to second trimester ultrasound biometries and the actual calender time elapsed in days. Late fetal growth was expressed as the observed versus expected birthweight according to gestational age (GA). RESULTS: The surgery-to-conception interval ranged from 3 to 1851 days with a mean value of 502 (SD, 351) days. The mean "fetal growth index" was 0.99 (SD, 0.02) days/day and thus significantly lower than in the background population (mean, 1.04 (SD, 0.09) days/day, p<0.0001). The proportion of infants being small for gestational age was 18.8% and the proportion of large for gestational age infants was 6.7%. The correlation coefficients between surgery-to-conception time and "fetal growth index" and birthweight according to GA were 0.01 (p = 0.8) and 0.04 (p = 0.4), respectively. CONCLUSION: Fetal growth index was lower than reported in the background population. No correlation was found between the surgery-to-conception interval and early or late fetal growth in pregnancies conceived after gastric bypass surgery

Pregnancy characteristics and outcome in women with gastric bypass prior to their pregnancy compared to all pregnancies registered in the Danish Fetal Medicine Database in 2008.

<p><i>GA = Gestational age, NT = Nuchal Translucency.</i></p>a<p><i>Continuous normally distributed data were compared with Student's t-test, unpaired using two-sided p-values.</i></p>b<p><i>missing values on GA in 46/387.</i></p>c<p><i>missing values on birth weight in 51/387.</i></p

Relation between surgery-to-conception time and fetal growth index.

<p>Relation between surgery-to-conception time and fetal growth index.</p

Maternal characteristics of women with gastric bypass prior to their pregnancy compared to all pregnancies registered in the Danish Fetal Medicine Database in 2008.

a<p><i>Continuous normally distributed data were compared with Student's t-test and proportions between dichotomous outcomes were compared with χ²-square tests using two-sided p-values.</i></p>b<p><i>Data on Smoking were missing in 4/387 women in the gastric bypass group and 677/57,368 in the general pregnant population.</i></p>c<p><i>Body mass index. Missing values on BMI in 8/387.</i></p>d<p><i>ICSI, IVF and insemination, missing information on 9/387 in the gastric by pass group and 5214/57,368 in the general pregnant population.</i></p>e<p><i>not significant.</i></p

Relation between surgery-to-conception time and fetal birthweight according to expected for gestational age.

<p>Relation between surgery-to-conception time and fetal birthweight according to expected for gestational age.</p