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Pregnancies and deliveries in patients
with Charcot–Marie–Tooth disease
Jana Midelfart Hoff, MD; Nils Erik Gilhus, MD, PhD; and Anne Kjersti Daltveit, PhD Abstract—Objective: To investigate the effect of maternal Charcot–Marie–Tooth disease (CMT) on pregnancy and deliv-
ery. Methods: Data from the Medical Birth Registry of Norway 1967 to 2002 were surveyed. This registry has compulsory
notification of all births. One hundred eight births by mothers with CMT were identified. The reference group consisted of
all 2.1 million births by mothers without CMT. Results: Women with CMT had a higher occurrence of presentation
anomalies (9.3 vs 4.5%; p ϭ 0.04) and bleeding post partum (12.0 vs 5.8%; p ϭ 0.02). The rate of operative delivery was
twice that of the reference group (29.6 vs 15.3%; p ϭ 0.002), and forceps was used three times as often in the CMT group
(9.3 vs 2.7; p Ͻ 0.001). The majority of CMT cesarean sections were emergency sections. Conclusion: Charcot–Marie–Tooth
disease increases the risk for complications during delivery, which is linked to a higher occurrence of emergency interven-
tions during birth.
There have been few studies on how Charcot–Marie– elements: 1) a standardized form used during pregnancy by the Tooth disease (CMT) can affect pregnancy, birth and patient’s physician, 2) oral information given by the patient whenadmitted to the hospital, and 3) information from doctor and mid- the newborn.1-3 There has been more emphasis on wife about the actual delivery and the newborn. Thus, the notifi- diagnosis in the fetus.4,5 We sought to examine how cation form contains information on the mother’s health before CMT affects pregnancy and the birth process. With and during pregnancy as well as information about the actual use of data from the Medical Birth Registry of Nor- birth and the newborn. Completion of the notification form is theresponsibility of the attending midwife. The form is co-signed by way (MBRN), a complete national survey of births in Norway from 1967, we found that CMT is an inde- Descriptive variables included year of birth, type pendent risk factor for complications during preg- of obstetric institution, age of mother (completed years), sex of child, birth order (parity), birth weight (g), and gestational age incompleted weeks/prematurity. Preterm birth was defined accord-ing to the World Health Organization as delivery prior to 37completed weeks of gestation. Selected outcome variables included Methods.
MBRN was established in 1967 and is based on the induction of birth (any induction, perforation of amniotic mem- compulsory notification of all births in Norway after 16 weeks ofgestation.6 The notification form is sent within 9 days after birth branes, infusion with oxytocin and prostaglandin), interventions or discharge from the maternity clinic. The registry contains data (any intervention, perforation of amniotic membranes, cesarean on the mother’s demographic variables, the pregnancy, the deliv- section, use of vacuum extractor or forceps, and manual removal ery, and the newborn. An unchanged birth notification form was of placenta), delivery complications (any complication, premature in use from 1967 to 1998. A revised and more detailed form has rupture of amniotic membranes, functional disorder of birth, inju- been used since December 1, 1998. Complete ascertainment of the ries in the birth canal, bleeding post partum of Ͼ500 mL, obstruc- births is ensured through a record linkage with the National Pop- tion of birth process, presentation anomalies, and complications ulation Registry run by Statistics Norway. The registry is placed regarding the umbilical cord), perinatal mortality, congenital con- under the Norwegian Institute of Public Health.
ditions, and birth defects. After 1988, cesarean sections were clas- The data comprised all births registered in MBRN between sified as elective or not. Functional disorder of birth is a collective January 1, 1967, and December 31, 2002. Through the unique term for prolonged delivery (lasting Ͼ24 hours), cervical dystocia, 11-digit personal identification of all inhabitants in Norway, we uterine atony, and uterine dysfunction. Perinatal mortality was traced the births of each mother consecutively. The CMT group defined as all fetal deaths after 16 weeks of gestation as well as consisted of all births by mothers who for at least one birth had deaths during the first week of life. The birth defects were defined been recorded with a CMT diagnosis: 108 births by 49 mothers.
as severe and not severe, according to a definition by MBRN based The reference group consisted of all births by women without a on the International Classification of Diseases, 8th rev. (1967 to CMT diagnosis at any birth (n ϭ 2,102,971).
The CMT diagnosis was established through clinical and neu- We compared the CMT and reference group using rophysiologic examinations as well as inheritance patterns, ac- cross-tables with Pearson ␹2 test. Two-sided p values of Ͻ0.05 cording to international standards,7,8 described by a Norwegian were interpreted as significant. Arithmetic mean was calculated expert group in 2001.9 In two Norwegian studies, both published for each group regarding gestational age, gestational weight, in 2001,10,11 all patients were diagnosed with CMT on the basis of mother’s age, and parity. The analyses were based on crude and both clinical and neurophysiologic (neurography, electromyogra- adjusted measures. The following were considered as potential phy) examinations. Genetic testing12 was done routinely from 2001 confounders: mother’s age in completed years at birth (Ͻ25, 25 to in cases where the diagnosis was suspected (Department of Medi- 34, 35ϩ), period of birth (1967 to 1980, 1981 to 1990, 1991 to cal Genetics, Haukeland University Hospital, Bergen, Norway).
2002), birth order (first child, second child, third or more child), The information in the birth notification form is based on three and type of birth institution (university hospital, other). Logistic From the Section for Neurology (Drs. Hoff and Gilhus), Department of Clinical Medicine, and Section for Epidemiology and Medical Statistics (Dr. Daltveit),Department of Public Health and Primary Health Care, University of Bergen, Department of Neurology (Dr. Gilhus), Haukeland University Hospital, andMedical Birth Registry of Norway (Dr. Daltveit), Bergen, Norway.
Received April 20, 2004. Accepted in final form October 11, 2004.
Address correspondence and reprint requests to Dr. J.M. Hoff, Section for Neurology, Department of Clinical Medicine, University of Bergen, Bergen,Norway; e-mail: jana.midelfart.hoff@helse-bergen.no Copyright 2005 by AAN Enterprises, Inc.
Table 1 Demographic characteristics in CMT and reference
births. Twenty-four of the 49 women had the CMT diagno- sis recorded in all their births. Thirty-three were recordedwith the CMT diagnosis in one birth, 15 in two births, and 1 woman in three births. No differences were found re- garding mean birth weight, mean birth order (parity), mean gestational age, or prematurity comparing the CMTgroup and the reference group.
The rate for operative delivery (cesarean section and vacuum/forceps) was significantly increased in the CMT group (table 2). This was due mainly to an increased rate of forceps. In contrast, total interventions during birth didnot occur more frequently in the CMT group. Cesarean section was performed in 17 CMT cases. Five were under- taken because of a fetal presentation anomaly. Among the remaining 12 cases, child asphyxia was notified in 1, pre- eclampsia in the mother in 1, and pelvic contractures in 3.
Only 3 of the 10 cesarean sections performed after 1988 were classified as elective, 1 of them due to fetal hydro- cephalus. The remaining seven were emergencies; in six of them, the mother had the CMT diagnosis notified. The number of births requiring any induction (infusion of oxy-tocin or pitocin, perforation of amniotic membranes) was not raised in the CMT group (12.0 vs 13.3% in the refer- ence group; p ϭ 0.7). The use of forceps was related toabnormal fetal presentation in 2 of 10 cases (both with The total use of operative delivery was more stable in regression was performed. To avoid assumptions of linear associa- the CMT group than in the reference group over time tions, all covariates were represented as indicator variables in the (table 3). The main difference between the CMT group and model. The presented adjusted results are based on adjustment the reference group was that the use of forceps in the CMT for period of birth, as this was the only variable that changed theestimates. The analyses were performed in SPSS 11.0 (SPSS, Chi- group continued to be higher in all periods (see table 3).
cago, IL). Estimates of necessary sample size to obtain an 80% There were few or no differences regarding use of vacuum power to detect significant differences in use of intervention be- and total number of cesarean section. As for these two tween the reference group and the patient group were calculated procedures, a power analysis was carried throughout to in S-Plus (version 6.1 for Windows). The power calculations were evaluate our results. For cesarean section, where the pro- based on the observed proportions of intervention in the twogroups, a type 1 error of 5.0%, and a two-sided test.
portion was 9.0% in the reference group and 15.7% in thepatient group, 183 CMT patients and a correspondingly Results.
We identified 108 births by 49 women with a higher number of individuals in the reference group would diagnosis of CMT in one or more of their births (table 1).
have been necessary to obtain an 80% power to detect a The diagnosis was positively recorded in 66 of the 108 significant difference in the cesarean section rate between Table 2 Interventions during birth and obstetric complications in women with CMT (n ϭ 108) and reference group (n ϭ 2,102,971),
adjusted for period of birth
* Pearson ␹2, p value.
† Data from 1988 onward.
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Table 3 Operative delivery in CMT (n ϭ 108) and reference (n ϭ 2,102,971) group according to period of birth
the two groups. Thus, the number needed was close to the occurred more frequently in the CMT group, the risk actual 108 patients, and power was found not to be de- doubled compared with the reference group.
creased considerably. As for vacuum extraction, where the There is convincing evidence that this study in- proportion was 3.9% in the reference group and 5.6% in cludes all women with CMT giving birth in Norway the patient group, the necessary number of CMT patients from 1967 to 2002. We were able to link each moth- would have been 1,195 to detect a significant difference.
er’s consecutive births, and this showed a high con- Presentation anomalies for the child occurred with in- sistency in the diagnosis of CMT for consecutive creased frequency in the CMT group (see table 2). Breech births, suggesting no or a very low proportion of false presentation was recorded in four births and abnormalcephalic presentation in six.
positives in our data set. This is important, as false Increased bleeding post partum occurred more com- positives would have diluted any effects.
monly in the CMT group (see table 2). Among the 13 cases Norway has until recently had a low total rate of with bleeding, 2 women had undergone cesarean section, 4 cesarean section, and the rate is still substantially had uterine dysfunction and uterine atony notified, and 2 lower than in many other countries: 15.1% in 2002 had retained placental fragments. In five cases, no other compared with 26.0% in the USA.13,14 As the policy complication or condition was notified.
toward cesarean section has become less restrictive, The total rate of birth complications was not raised in there has been a tendency toward performing elec- the CMT group (see table 2). No increased incidence was tive sections in patients considered with an in- found for obstruction of the birth process (3.7% in the CMT creased risk.15 There was no such trend among the group vs 1.9% in the reference group; p ϭ 0.3) or for func- mothers with CMT. The majority were emergency tional disorder of birth or injuries in the birth canal (8.3% sections, both when the diagnosis was recorded on in the CMT group vs 6.5% in the reference group; p ϭ 0.7).
the birth registration form and when it was not. This No increased incidence was found for premature rupture of implies that the mother’s clinical condition prior to amniotic membranes. The perinatal mortality for the CMT delivery—and her disorder—were not regarded as group was not raised compared with the reference group(1.9 vs 1.6%; p ϭ 0.9). One CMT child was born with representing any increased risk. The frequent use of hydrocephalus and another with foot deformities. The total the emergency procedures of vacuum and forceps in rate of severe birth defects was not increased compared the CMT group supports this theory. Contrary to the with the reference group (1.9 vs 1.9%; p ϭ 1.0).
general trend in obstetric care,16 the use of forceps inthe CMT group remained high throughout the whole Discussion.
time period, further demonstrating the real need for needed operative intervention during delivery. Forceps emergency delivery in mothers with CMT.
and vacuum were employed twice as often in this Presentation anomalies occurred more frequently group. The majority of cesarean sections performed on in the CMT group than in the reference group. This women with CMT were undertaken as emergencies.
is similar to what is seen for myotonic dystrophy.17 Both presentation anomalies and bleeding post partum However, in myotonic dystrophy, the fetus is fre- February (1 of 2) 2005
quently severely affected by the mother’s genetic dis- References
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