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Adverse maternal outcomes associated with fetal macrosomia: what are the risk factors beyond birthweight?
© Fuchs et al.; licensee BioMed Central Ltd. 2013
Received: 27 November 2012
Accepted: 2 April 2013
Published: 8 April 2013
To identify risk factors, beyond fetal weight, associated with adverse maternal outcomes in delivering infants with a birthweight of 4000 g or greater, and to quantify their role in maternal complications.
All women (n = 1564) with singleton pregnancies who attempted vaginal delivery and delivered infants weighing at least 4000 g, in two French tertiary care centers from 2005 to 2008, were included in our study. The studied outcome was maternal complications defined as composite item including the occurrence of a third- or fourth-degree perineal laceration, or the occurrence of severe postpartum hemorrhage requiring the use of prostaglandins, uterine artery embolization, internal iliac artery ligation or haemostatic hysterectomy, or the occurrence of blood transfusion. Univariate analysis, multivariable logistic regression and estimation of attributable risk were used.
Maternal complications were increased in Asian women (adjusted odds ratio [aOR], 3.1; 95% confidence interval [CI], 1.1–9.3, Attributable risk (AR): 3%), in prolonged labor (aOR = 1.9 [95% CI; 1.1–3.4], AR = 12%) and in cesarean delivery during labor (aOR = 2.2 [95% CI; 1.3–3.9], AR = 17%). Delivering infants with a birthweight > 4500 g also increased the occurrence of maternal complications (aOR = 2.7 [95% CI; 1.4–5.1]) but with an attributable risk of only 10%. Multiparous women with a previous delivery of a macrosomic infant were at lower risk of maternal complications (aOR = 0.5 [95% CI; 0.2–0.9]).
In women delivering infants with a birthweight of 4000 g or greater, some maternal characteristics as well as labor parameters may worsen maternal outcome beyond the influence of increased fetal weight.
A consistent increase in the mean birthweight and in the proportion of fetal macrosomia, defined as a birthweight greater than 4000 g, has been reported since the 1980s’ [1–4]. This trend may be linked to higher maternal weight gain during pregnancy, increase in frequencies of maternal obesity and diabetes, and reduced smoking in pregnant women [5, 6]. Primary concern about the birth of a macrosomic foetus is adverse neonatal outcomes including stillbirth and neonatal mortality secondary to birth asphyxia, shoulder dystocia, birth injury, metabolic disorders, and meconium aspiration syndrome. The occurrence of these unfavourable outcomes and their risks factors have been widely studied [7–11]. Similarily, maternal complications are increased in the setting of fetal macrosomia [7–9, 12–14]. These complications have been studied mainly by comparing women delivering macrosomic newborns to women delivering non-macrosomic newborns, thereby using fetal birth weight as a primary risk factor. Little attention has been paid to parameters other than fetal weight that may specifically occur in women delivering macrosomic infants.
The objective of this study was to identify risks factors, other than fetal birth weight, for maternal complications in women who delivered macrosomic infants.
All women with singleton pregnancies who attempted a vaginal birth and delivered infants weighing at least 4000 g, in two French tertiary care centers of Paris suburbs (Hôpital Antoine Béclère, Clamart and Centre Hospitalier Intercommunal de Poissy-Saint Germain, Poissy) from January 2005 through December 2008 were included. Demographic characteristics, obstetrical history, pregnancy and neonatal data were registered prospectively in hospitalization databases (approval by CNIL, the French Data Protection Authority, under the notification number 1181076). Three types of maternal complications were considered: 1) the occurrence of a third- or fourth-degree perineal laceration; 2) a severe postpartum hemorrhage defined as persistent bleeding more than 500 cc requiring the use of prostaglandins (sulprostone), uterine artery embolization, internal iliac artery ligation or haemostatic hysterectomy; 3) the need for blood transfusion. A composite criterion was then built based on the occurrence of at least one of these 3 types of maternal complications. The criterion was named “MC”, and was used as the primary outcome in this study. Apart from fetal weight, risk factors for MC were screened among demographic characteristics, obstetrical history, pregnancy and neonatal data.
Although neonatal complications were not the primary interest of this study, two of them were considered for qualitative analysis: shoulder dystocia, defined as the need to use obstetrical maneuvers to extract the body of the fetus after head delivery; and brachial plexus injury, defined as paralysis or inability to actively move of an upper extremity as determined and diagnosed by pediatricians and neonatologists.
After a descriptive study of maternal characteristics and obstetrical outcomes, we performed multiple logistic regression analysis to best fit the model for predicting our composite criterion, MC . Birthweight was included as a dichotomous variable (lower or greater than 4500 g). Other variables with p values < 0.2 in the univariate analysis, or known risk factors of MC (such as diabetes, body mass index and gestational age at delivery) were entered into the multivariate logistic regression model . A systematic adjustment was made for the given hospital centre. In case of a statistically significant odds ratio greater than 1, we computed attributable risk  for the corresponding risk factor. Regardless of the certainty of causal association, the calculated attributable risk serves to quantify a portion of each factor present in MC.
In the context of macrosomia, the place given to caesarean sections is questionable. On the one hand, they may prevent maternal complications (in particular perineal lacerations), on the other hand, they may be considered as a complication of delivery by themselves. We chose to exclude women with elective cesarean delivery (defined as cesarean deliveries scheduled 8 hours or more before delivery and performed as intended ) since they were mainly planned due to maternofetal dystocia. However, we included other cesarean deliveries since they reflected a prolonged and difficult labor that may implicate maternal complications. To validate our selection of cesarean sections, we performed two sensitivity analyses on all cesarean sections, both elective and non-elective: the first with the same composite criteria as MC, and the second including elective cesarean delivery for macrosomic suspicion as a supplementary criteria for MC.
Statistical analyses were performed using STATA® v.11 (Stata Corporation, College Station, TX, USA) software.
Results and discussion
Maternal age (years)
Mean +/− SD [range]
30.8 +/− 4.8 [17–46]
< 30 y
Asia and India
America (Northern and Southern)
Diet controlled gestational diabetes
Gestational diabetes requiring insulin
Route of delivery
Cesarean during labor
3rd or 4th degree perineal tears §
Severe postpartum hemorrhage
Uterine artery embolization
Internal iliac artery ligation
Brachial plexus injury
Mean birthweight was 4207 g (95% CI [4010; 4590]). Eight percent weighed more than 4500 g and 0.4% more than 5000 g. The gender was male in 67% of newborns and the 5 minute Apgar score was greater than 7 in 98.5% of cases. Seventy three newborns (4.7%) were admitted to neonatal intensive care unit, mainly for respiratory distress (43%) or hypoglycemia (30%), and for a median duration of 2 days [range 1–10].
Factors significantly associated with MC in univariate analysis were patient’s origin, history of a macrosomic infant vaginally delivered, prolonged duration of labor, cesarean delivery during labor and neonatal birth weight.
Risks factors of maternal complications***
aOR [95% CI]*
Patient’s age (years)
Composite of parity and previous vaginal delivery of a macrosomic infant
Multiparous without previous macrosomic delivery
Multiparous with previous macrosomic delivery
Obesity (body mass index > 30 kg/m 2 )
Duration of labor
< 10 hours
Cesarean during labor
Birth weight (grams)
Infant gender (Male)
We report that the occurrence of maternal complications when attempting vaginal birth is 6% among women delivering infants with a birthweight ≥ 4000 g. The prevalence of macrosomic infants and the characteristics of our sample were very similar to those depicted in previous studies [4, 5, 11, 19–21]. The risk factors for MC were not only fetal weight but also Asian origin, long duration of labor, and cesarean during labor. It should also be noted that multiparous women with a previous vaginal delivery of a macrosomic child had a decreased risk of MC.
It is well known that maternal and neonatal morbidity increases with birthweight and especially over 4500 g [5, 9, 11, 12, 22]. Zhang et al.  have shown a J-shaped birthweight-specific perinatal mortality and morbidity curves, with 2 important thresholds: 4500 g and 5000 g. Over those two thresholds, complications are dramatically increased. The 4500 g threshold was always present in our study, but to a lesser extent since the sample was limited to newborns heavier than 4000 g. In turn, this intended limitation allowed us to study other factors since it decreased the role of birthweight in MC. Moreover, the large and unselected sample (all women with a newborn heavier than 4000 g were included) provided a sufficient statistical power and results that are potentially generalizable.
Handa et al.  found that perineal tears risk increased 2-fold in case of macrosomia, but increased also in Asian women, Filipinas, and Indian women compared to white women with OR = 1.37, 1.63 and 2.50 respectively for anal sphincter laceration. Our findings confirmed these results. Ethnic origins may be associated with differences in body type and variations in perineal anatomy [23, 24]. These particularities in body tissue may increase the risk of perineal tears and, as found in our study for Asian women, may favor maternal complications.
The potentially “protective” effect of having previously vaginally delivered a macrosomic infant has been reported by Mahony et al. . Maternal perineal tissues have therefore already experienced macrosomic delivery and are more likely to experience an uneventful subsequent delivery.
Maternal diabetes as well as body mass index were not significantly associated with maternal complication in our study. However, it is well known that maternal diabetes is associated with shoulder dystocia and also perineal tears . Data from the literature also support that maternal obesity is associated with increased postpartum hemorrhage [27, 28] and prolonged labors . This discrepancy in our study may be explained by the fact that the role of these factors in maternal complications is primarily through birth weight. Another explanation may also be that the proportion of maternal diabetes and obese patients remained consistent, albeit relatively low, in our sample (respectively 7.3% and 11.5%).
Cesarean delivery is a known risk factor of postpartum hemorrhage especially when it occurs during labor and after a long duration of labor [30, 31]. Similarly, prolonged labor with the use of oxytocin is the main contributor of uterine atony that account for 79% of the cases of postpartum hemorrhage . In fact, the occurrence of post-partum hemorrhage is more increased when one of those parameter is associated with macrosomia [14, 32]. In our study, both parameters (cesarean and prolonged labor) appear to increase significantly the occurrence of MC, probably through their influence on post-partum hemorrhage. Those results are in agreement with the literature but quantification of their association after adjusting for birth weight has never been reported.
In addition, we computed the attributable risk as an alternative means to evaluate the role of each risk factor in maternal complications associated with fetal macrosomia , Although it can not ensure the causality of association the attributable risk quantifies the magnitude of the proportion of MC that could be avoided by removing the risk factor. Attributable risk estimation is particularly useful for factors that may be modified, but is useful to a lesser extent for unchangeable factors such as ethnic origin.
Estimation of attributable risks enabled us to precisely identify that only 10% of MC may be attributed to a birth weight greater than 4500 g, which is almost identical to the contribution of prolonged labor. Cesarean during labor appeared to be the most important factor with attributable risk equal to 17%. This could be explained by the fact it is likely responsible for the highest rates of post partum haemorrhage and blood transfusion. Finally, as the sum of attributable risk did not reach 100%, we should also mentioned that a fraction of the cases of MC were not associated with identifiable risk factors.
Beyond the influence of increased fetal weight, Asian origins, prolonged labor and cesarean delivery during labor may worsen maternal outcome. Obstetricians should be aware of these these parameters that could led to maternal complications such as severe perineal tears or postpartum hemorrhage.
Written informed consent was obtained from the patient for publication of this report and any accompanying images.
- Alberman E: Are our babies becoming bigger?. J R Soc Med. 1991, 84 (5): 257-260.PubMedPubMed CentralGoogle Scholar
- Arbuckle TE, Sherman GJ: An analysis of birth weight by gestational age in Canada. Cmaj. 1989, 140 (2): 157-160.PubMedPubMed CentralGoogle Scholar
- Skjaerven R, Gjessing HK, Bakketeig LS: Birthweight by gestational age in Norway. Acta Obstet Gynecol Scand. 2000, 79 (6): 440-449. 10.1080/j.1600-0412.2000.079006440.x.View ArticlePubMedGoogle Scholar
- Blondel B, Kermarrec M: La situation perinatale en France en 2010. Etude et resultats. 2010, 775: 1-8.Google Scholar
- Boulet SL, Alexander GR, Salihu HM, Pass M: Macrosomic births in the united states: determinants, outcomes, and proposed grades of risk. Am J Obstet Gynecol. 2003, 188 (5): 1372-1378. 10.1067/mob.2003.302.View ArticlePubMedGoogle Scholar
- Kramer MS, Morin I, Yang H, Platt RW, Usher R, McNamara H, Joseph KS, Wen SW: Why are babies getting bigger? Temporal trends in fetal growth and its determinants. J Pediatr. 2002, 141 (4): 538-542. 10.1067/mpd.2002.128029.View ArticlePubMedGoogle Scholar
- Boyd ME, Usher RH, McLean FH: Fetal macrosomia: prediction, risks, proposed management. Obstet Gynecol. 1983, 61 (6): 715-722.PubMedGoogle Scholar
- Meshari AA, De Silva S, Rahman I: Fetal macrosomia–maternal risks and fetal outcome. Int J Gynaecol Obstet. 1990, 32 (3): 215-222. 10.1016/0020-7292(90)90348-O.View ArticlePubMedGoogle Scholar
- Oral E, Cagdas A, Gezer A, Kaleli S, Aydinli K, Ocer F: Perinatal and maternal outcomes of fetal macrosomia. Eur J Obstet Gynecol Reprod Biol. 2001, 99 (2): 167-171. 10.1016/S0301-2115(01)00416-X.View ArticlePubMedGoogle Scholar
- Raio L, Ghezzi F, Di Naro E, Buttarelli M, Franchi M, Durig P, Bruhwiler H: Perinatal outcome of fetuses with a birth weight greater than 4500 g: an analysis of 3356 cases. Eur J Obstet Gynecol Reprod Biol. 2003, 109 (2): 160-165. 10.1016/S0301-2115(03)00045-9.View ArticlePubMedGoogle Scholar
- Zhang X, Decker A, Platt RW, Kramer MS: How big is too big? The perinatal consequences of fetal macrosomia. Am J Obstet Gynecol. 2008, 198 (5): e511-e516.View ArticleGoogle Scholar
- Gregory KD, Henry OA, Ramicone E, Chan LS, Platt LD: Maternal and infant complications in high and normal weight infants by method of delivery. Obstet Gynecol. 1998, 92 (4 Pt 1): 507-513.PubMedGoogle Scholar
- Handa VL, Danielsen BH, Gilbert WM: Obstetric anal sphincter lacerations. Obstet Gynecol. 2001, 98 (2): 225-230. 10.1016/S0029-7844(01)01445-4.PubMedGoogle Scholar
- Stotland NE, Caughey AB, Breed EM, Escobar GJ: Risk factors and obstetric complications associated with macrosomia. Int J Gynaecol Obstet. 2004, 87 (3): 220-226. 10.1016/j.ijgo.2004.08.010.View ArticlePubMedGoogle Scholar
- Harrell F: Regression modeling strategies: with applications to linear models, logistic regression, and survival analysis. 2001, New York: SpringerView ArticleGoogle Scholar
- Royston P, Sauerbrei W: Multivariable model-building. A pragmatic approach to regression analysis based on fractional polynomials for modelling continuous variables. 2008, Chichester: John Wiley & SonsGoogle Scholar
- Benichou J: A review of adjusted estimators of attributable risk. Stat Methods Med Res. 2001, 10 (3): 195-216. 10.1191/096228001680195157.View ArticlePubMedGoogle Scholar
- Fuglenes D, Aas E, Botten G, Oian P, Kristiansen IS: Maternal preference for cesarean delivery: do women get what they want?. Obstet Gynecol. 2012, 120 (2 Pt 1): 252-260.View ArticlePubMedGoogle Scholar
- Batallan A, Goffinet F, Paris-Llado J, Fortin A, Breart G, Madelenat P, Benifla JL: Fetal macrosomia: management, obstetrical and neonatal results. Multicenter case–control study in 15 maternity hospitals in Paris and the Ile de France area. Gynecol Obstet Fertil. 2002, 30 (6): 483-491. 10.1016/S1297-9589(02)00364-8.View ArticlePubMedGoogle Scholar
- Siggelkow W, Boehm D, Skala C, Grosslercher M, Schmidt M, Koelbl H: The influence of macrosomia on the duration of labor, the mode of delivery and intrapartum complications. Arch Gynecol Obstet. 2008, 278 (6): 547-553. 10.1007/s00404-008-0630-7.View ArticlePubMedGoogle Scholar
- Blondel B, Supernant K, Du Mazubrun C, Breart G: Enquête nationale perinatale 2003 - Rapport de fin d’étude. 2005, Paris: INSERMGoogle Scholar
- Bjorstad AR, Irgens-Hansen K, Daltveit AK, Irgens LM: Macrosomia: mode of delivery and pregnancy outcome. Acta Obstet Gynecol Scand. 2010, 89 (5): 664-669. 10.3109/00016341003686099.View ArticlePubMedGoogle Scholar
- Green JR, Soohoo SL: Factors associated with rectal injury in spontaneous deliveries. Obstet Gynecol. 1989, 73 (5 Pt 1): 732-738.PubMedGoogle Scholar
- Zacharin R: “A Chinese anatomy”—the pelvic supporting tissues of the Chinese and Occidental female compared and contrasted. Aust N Z J Obstet Gynecol. 1977, 17: 1-11. 10.1111/j.1479-828X.1977.tb02661.x.View ArticleGoogle Scholar
- Mahony R, Walsh C, Foley ME, Daly L, O’Herlihy C: Outcome of second delivery after prior macrosomic infant in women with normal glucose tolerance. Obstet Gynecol. 2006, 107 (4): 857-862. 10.1097/01.AOG.0000203340.09961.0b.View ArticlePubMedGoogle Scholar
- Adams KM, Li H, Nelson RL, Ogburn PL, Danilenko-Dixon DR: Sequelae of unrecognized gestational diabetes. Am J Obstet Gynecol. 1998, 178 (6): 1321-1332. 10.1016/S0002-9378(98)70339-4.View ArticlePubMedGoogle Scholar
- Naef RW, Chauhan SP, Chevalier SP, Roberts WE, Meydrech EF, Morrison JC: Prediction of hemorrhage at cesarean delivery. Obstet Gynecol. 1994, 83 (6): 923-926. 10.1097/00006250-199406000-00004.View ArticlePubMedGoogle Scholar
- Stones RW, Paterson CM, Saunders NJ: Risk factors for major obstetric haemorrhage. Eur J Obstet Gynecol Reprod Biol. 1993, 48 (1): 15-18. 10.1016/0028-2243(93)90047-G.View ArticlePubMedGoogle Scholar
- Vahratian A, Zhang J, Troendle JF, Savitz DA, Siega-Riz AM: Maternal prepregnancy overweight and obesity and the pattern of labor progression in term nulliparous women. Obstet Gynecol. 2004, 104 (5 Pt 1): 943-951.View ArticlePubMedGoogle Scholar
- Bateman BT, Berman MF, Riley LE, Leffert LR: The epidemiology of postpartum hemorrhage in a large, nationwide sample of deliveries. Anesth Analg. 2010, 110 (5): 1368-1373. 10.1213/ANE.0b013e3181d74898.View ArticlePubMedGoogle Scholar
- Oyelese Y, Ananth CV: Postpartum hemorrhage: epidemiology, risk factors, and causes. Clin Obstet Gynecol. 2010, 53 (1): 147-156. 10.1097/GRF.0b013e3181cc406d.View ArticlePubMedGoogle Scholar
- Sosa CG, Althabe F, Belizan JM, Buekens P: Risk factors for postpartum hemorrhage in vaginal deliveries in a Latin-American population. Obstet Gynecol. 2009, 113 (6): 1313-1319.View ArticlePubMedPubMed CentralGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2393/13/90/prepub
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