Epidemiology of Macrosomia in Saudi Arabia: An Analysis of 12,045 Pregnancies from the Riyadh Mother and Baby Multicenter Cohort Study (RAHMA) Database.

Objective: To investigate the prevalence, risk factors, and complications associated with delivering macrosomic babies.

Methods: Singleton term pregnancies (12,045) were studied. Macrosomia was categorized using the following two definitions: birthweight > 4 kg and birthweight ≥ 90th percentile (3.7 kg). Regression models were developed to identify significant risk factors for macrosomia such as maternal age, parity, pre-pregnancy body mass index, gestational weight gain, and hyperglycemia. Other models were constructed to identify the independent effect of macrosomia on outcomes such as shoulder dystocia, emergency cesarean section, stillbirth, and low APGAR scores.

Results: The 50th centile birth weight of Saudi term infants is 3.18 kg; the 90th and 95th centiles were 3.70 and 3.91 kg, respectively. The prevalence of macrosomia (>4 kg) was 3.4%. The likelihood of macrosomia was associated with maternal age >40 years for newborns >4 kg, OR = 1.88, 95% CI (1.02-3.48), and maternal age < 18 for newborns ≥90th centile, OR = 5.23, 95% CI, (1.05-26.06). Regardless of the classification of macrosomia, it was associated with gestational age ≥41 weeks, parity > 4, pre-pregnancy BMI > 30, and maternal hyperglycemia. Macrosomia, using either definition, was associated with increased risk of shoulder dystocia, OR = 11.45, 95% CI (4.12-31.82) and OR = 9.65, 95% CI (3.89-23.94), and emergency CS, OR = 2.03, 95% CI (1.36-3.08) and OR = 1.77, 95% CI (1.34-1.52), for birthweight > 4 kg and ≥90th centile, respectively. Furthermore, newborns whose weights >4 kg were at greater risk to be stillborn, OR = 4.24, 95% CI (1.18-15.20), and to have low APGAR scores at birth, OR = 3.69, 95% CI (1.25-10.98).

Conclusion: The risk of macrosomia among Saudi women significantly increases with maternal age, parity, gestational age, hyperglycemia, and pre-pregnancy obesity. Regardless of the definition used, delivering a macrosomic baby was associated with risks of shoulder dystocia and emergency cesarean section. Newborns (>4 kg) were at greater risk of stillbirth and low APGAR scores.