Carbimazole, Thiamazole (Methimazole)

Exposed non-exposed, cohort studies

Study Country
Study period
Study design
Data source Exposure definition Non-exposure definition Exposition period Sample size
(exposed/unexposed) Or (case / control)
Remarks Overall risk of bias
Andersen (control exposed to PTU)
2019
Denmark
1997 - 2016
population based cohort retrospective
Danish nationwide register-based cohort study (NRBC) Use of MMI/CMZ in early pregnancy (redeemed prescriptions of the drugs in the period ranging from six months prior to pregnancy start up to and including the 10th week of pregnancy) exposed to other treatment, sick
Use of PTU in early pregnancy (redeemed prescriptions of the drugs in the period ranging from six months prior to pregnancy start up to and including the 10th week of pregnancy)
early pregnancy 1574 / 889 Update of the previous study Andersen 2013 '(children born from 1996 to 2008) with this longer study (1997-2016). NA
The Danish National Prescription Register (DNPR) includes information on redeemed prescriptions of drugs coded according to the Anatomical Therapeutical Classification (ATC) system, and drugs used for the treatment of thyroid disease are included in the ATC group: H03.
Andersen (control unexposed, disease free)
2019
Denmark
1997 - 2016
population based cohort retrospective
Danish nationwide register-based cohort study (NRBC) Use of MMI/CMZ in early pregnancy (redeemed prescriptions of the drugs in the period ranging from six months prior to pregnancy start up to and including the 10th week of pregnancy) unexposed, disease free
Children whose mother had no diagnosis of hyperthyroidism, no registration of thyroid surgery and no redeemed prescription of ATD or Levothyroxine before, during or after the pregnancy under study and up to December 31, 2017
early pregnancy 1574 / 1159181 Update of the previous study Andersen 2013 '(children born from 1996 to 2008) with this longer study (1997-2016). NA
The Danish National Prescription Register (DNPR) includes information on redeemed prescriptions of drugs coded according to the Anatomical Therapeutical Classification (ATC) system, and drugs used for the treatment of thyroid disease are included in the ATC group: H03.
Andersen 2014 (control unexposed, disease free)
2014
Denmark
1996 - 2008
population based cohort retrospective
Danish nationwide register-based cohort study Live-born children exposed to MMI/CMZ in early pregnancy unexposed, disease free
Children born to mothers with no prescriptions of ATD and/or thyroid hormones redeemed 1995 to 2008 and no diagnosis of hyperthyroidism in the DNHR from 1977 to 2008.
early pregnancy 1097 / 811730 This study is a extension (focused on subtype of congenital heart defect) of the study previously published (Andersen et al. 2013), using methods previously described in detail. Therefore, methods are extracted from the article Andersen et al. 2013. NA
Danish National Prescription Register. Thyroid hormones (ATC H03A) and ATD (ATC H03B) are sold solely as prescription drugs in Denmark.
Andersen 2017 (control exposed to PTU)
2017
Sweden
2006 - 2012
population based cohort retrospective
Swedish nationwide register-based cohort study The child was defined as exposed to MMI/CMZ in early pregnancy if the mother had at least one redeemed prescription of ATD less than six months before the estimated pregnancy start and before the 11th gestational week. exposed to other treatment, sick
Children born to mothers who were treated with PTU in early pregnancy if the mother had at least one redeemed prescription of ATD less than six months before the estimated pregnancy start and before the 11th gestational week.
early pregnancy 162 / 218 Subanalyze of live-born children exposed to MMI/CMZ (n = 162) in early pregnancy versus PTU. The study also analyzed live-born children exposed to PTU (n = 218), to MMI/CMZ and PTU (n= 66) in early pregnancy. TOTAL : n =446. NA
Information on maternal use of ATDs was obtained from the Swedish Prescribed Drug Register (SPDR) which holds data on all prescriptions drugs in Swedish since 2005.
Andersen 2017 (control unexposed, disease free)
2017
Sweden
2006 - 2012
population based cohort retrospective
Swedish nationwide register-based cohort study The child was defined as exposed to MMI/CMZ in early pregnancy if the mother had at least one redeemed prescription of ATD less than six months before the estimated pregnancy start and before the 11th gestational week. unexposed, disease free
Children born to mothers with no redeemed prescriptions of ATD or thyroid hormones from 2005 to 2014 and no diagnosis of hyperthyroidism registered from 2005 to 2014 in the Swedish National Patient Register.
early pregnancy 162 / 682343 Subanalyze of live-born children exposed to MMI/CMZ (n = 162) in early pregnancy. The study also analyzed live-born children exposed to PTU (n = 218), to MMI/CMZ and PTU (n= 66) in early pregnancy. TOTAL : n =446. NA
Information on maternal use of ATDs was obtained from the Swedish Prescribed Drug Register (SPDR) which holds data on all prescriptions drugs in Swedish since 2005.
Andersen 2017 (control unexposed, sick)
2017
Sweden
2006 - 2012
population based cohort retrospective
Swedish nationwide register-based cohort study The child was defined as exposed to MMI/CMZ in early pregnancy if the mother had at least one redeemed prescription of ATD less than six months before the estimated pregnancy start and before the 11th gestational week. unexposed, sick
Children born to mothers who were treated with ATD more than one year before or more than one year after pregnancy and received no treatment with thyroid hormone in pregnancy.
early pregnancy 162 / 1551 Subanalyze of live-born children exposed to MMI/CMZ (n = 162) in early pregnancy. The study also analyzed live-born children exposed to PTU (n = 218), to MMI/CMZ and PTU (n= 66) in early pregnancy. TOTAL : n =446. NA
Information on maternal use of ATDs was obtained from the Swedish Prescribed Drug Register (SPDR) which holds data on all prescriptions drugs in Swedish since 2005.
Azizi
2002
Iran
Not specified
retrospective cohort
The Endocrine Research Center, Shaheed Beheshti University of Medical Sciences, Tehran, I.R. Iran Women with thyrotoxicosis who received methimazole (MMI) therapy during pregnancy, but not during lactation. unexposed (not otherwise specified)
Not exposed to methimazole (MMI) therapy during pregnancy (illness status not specified).
throughout pregnancy 23 / 30 NA
Women with thyrotoxicosis who had regular follow-up in the endocrine office were recalled.
Chen (control exposed to PTU)
2011
Taiwan
Jan 2005 - Dec 2005
retrospective cohort (claims database)
Two nationwide population-based data sets: Taiwan National Health Insurance Research Dataset (NHIRD) and the national birth certificate registry of Taiwan. Women with hyperthyroidism diagnosis, who were prescribed MMI treatment during pregnancy for more than 30 days during pregnancy. exposed to other treatment, sick
Women with hyperthyroidism diagnosis, who were prescribed PTU treatment during pregnancy for more than 30 days during pregnancy.
during pregnancy (anytime or not specified) 73 / 630 Subanalyze of live-born children exposed to MMI/CMZ (n = 73) during pregnancy. The study also analyzed live-born children exposed to PTU (n = 630) ; to MMI/CMZ or PTU (n= 703) during pregnancy. NA
Taiwan National Health Insurance Research Dataset (NHIRD) includes the cost of inpatient treatment and outpatient prescriptions.
Chen (control unexposed, disease free)
2011
Taiwan
Jan 2005 - Dec 2005
retrospective cohort (claims database)
Two nationwide population-based data sets: Taiwan National Health Insurance Research Dataset (NHIRD) and the national birth certificate registry of Taiwan. Women with hyperthyroidism diagnosis, who were prescribed MMI treatment during pregnancy for more than 30 days during pregnancy. unexposed, disease free
The remaining women in the database, excluding women with a diagnosis of hyperthyroidism anytime during the period 1996-2006.
during pregnancy (anytime or not specified) 73 / 14150 Subanalyze of live-born children exposed to MMI/CMZ (n = 73) during pregnancy. The study also analyzed live-born children exposed to PTU (n = 630) ; to MMI/CMZ or PTU (n= 703) during pregnancy. NA
Taiwan National Health Insurance Research Dataset (NHIRD) includes the cost of inpatient treatment and outpatient prescriptions.
Chen (control unexposed, sick)
2011
Taiwan
Jan 2005 - Dec 2005
population based cohort retrospective
Two nationwide population-based data sets: Taiwan National Health Insurance Research Dataset (NHIRD) and the national birth certificate registry of Taiwan. Women with hyperthyroidism diagnosis, who were prescribed MMI treatment during pregnancy for more than 30 days during pregnancy. unexposed, sick
Women with a diagnosis of hyperthyroidism not receiving antithyroid drug.
during pregnancy (anytime or not specified) 73 / 2127 Subanalyze of live-born children exposed to MMI/CMZ (n = 73) during pregnancy. The study also analyzed live-born children exposed to PTU (n = 630) ; to MMI/CMZ or PTU (n= 703) during pregnancy. NA
Taiwan National Health Insurance Research Dataset (NHIRD) includes the cost of inpatient treatment and outpatient prescriptions.
Di Gianantonio
2001
France, Germany, Israel, Italy, The Netherlands
Not specified
prospective cohort
10 Teratology Information Services (TIS) of the European Network of Teratology Information Services (ENTIS) Pregnant women exposed to MMI during the preconceptional period and/or the first trimester to treat hyperthyroidism. unexposed, disease free
Pregnant women exposed to nonteratogenic drugs during the preconceptional period and/or the first trimester
1st trimester 241 / 1089 NA
Prospective data were collected at the time of the inquiry and included questions on commercial preparation used, its dosage, indication for use, and the time during the pregnancy when it was taken.
Dwarakanath (control exposed to PTU)
1999
India
Not specified
retrospective cohort
Clinical data of the All India Institute of Medical Sciences, New Delhi, India Women with Graves' disease exposed to methimazole/neomercazole during pregnancy exposed to other treatment, sick
Women with Graves' disease exposed to propylthiouracil during pregnancy
at least 1st trimester, throughout pregnancy 8 / 8 NA
Women were advised regarding antithyroid drug during their pregnancies in the hospital.
Gianetti (control exposed to PTU)
2015
Italy
1992 - 2005
retrospective cohort
Clinical records of eight Italian Departments of Endocrinology retrospectively analyzed. Pregnancies of women being treated with MMI for Graves’ disease (GD) or toxic nodular goiter (TNG). exposed to other treatment, sick
Pregnancies of women being treated with PTU for Graves’ disease (GD) or toxic nodular goiter (TNG).
at least 1st trimester 124 / 52 Addition of the 2 groups of pregnancies exposed to MMI (euthyroid and hyperthyroid) and also for PTU. All patients included in the study received their diagnosis and started their therapies at least 3 months before pregnancy. NA
Records were reviewed retrospectively in order to collect data notably on specific antithyroid drug used and its dose.
Gianetti (control unexposed, sick)
2015
Italy
1992 - 2005
retrospective cohort
Clinical records of eight Italian Departments of Endocrinology retrospectively analyzed. Pregnancies of women being treated with MMI for Graves’ disease (GD) or toxic nodular goiter (TNG). unexposed, sick
Pregnant women who were affected by thyroid diseases but were euthyroid (either on LT4 therapy for hypothyroidism or without treatment) and did not receive any ATD medication during pregnancy.
at least 1st trimester 124 / 203 Addition of the 2 groups of pregnancies exposed to MMI (euthyroid and hyperthyroid at least twice during pregnancy). All patients included in the study received their diagnosis and started their therapies at least 3 months before pregnancy. NA
Records were reviewed retrospectively in order to collect data notably on specific antithyroid drug used and its dose.
Hawken (control exposed to PTU)
2016
France
2005 - 2012
retrospective cohort
Hospitals and open-care endocrinologists working in the Poitou-Charentes region, Foetuses exposed to carbimazole (CMZ) during pregnancy. exposed to other treatment, sick
Foetuses exposed to propylthiouracil (PTU) during pregnancy.
1st trimester, 2nd trimester, 3rd trimester 19 / 13 Treatment of Graves’ disease diagnosed during pregnancy (14 patients) : - 6 PTU en T1 => 0 malfo - 2 CMZ en T1 => 1 malfo Treatments in patients under SAT at the time of starting pregnancy (24 patients). - 7 PTU en T1 => 0 malfo - 17 CMZ en T1 => 3 malfo NA
Review of the files obtained by hospitals in the region after having contacted hospitals and open-care endocrinologists working in the Poitou-Charentes region.
Korelitz (control exposed to PTU)
2013
USA
2005 - 2009
retrospective cohort (claims database)
The MarketScan Commercial Claims and Encounters database Antithyroid (MMI only) drug use within 6 months before the pregnancy start date or during pregnancy exposed to other treatment, sick
Antithyroid (PTU only) drug use within 6 months before the pregnancy start date or during pregnancy
3 months (or more) before pregnancy or during pregnancy 108 / 915 NA
Prescription drug claims were used to determine ATD therapy.
Korelitz (control unexposed, disease free)
2013
USA
2005 - 2009
retrospective cohort (claims database)
The MarketScan Commercial Claims and Encounters database Antithyroid (MMI only) drug use within 6 months before the pregnancy start date or during pregnancy. unexposed, disease free
No Antithyroid (MMI or PTU) drug use in women without thyrotoxicosis.
3 months (or more) before pregnancy or during pregnancy 108 / 634858 NA
Prescription drug claims were used to determine ATD therapy.
Korelitz (control unexposed, sick)
2013
USA
2005 - 2009
retrospective cohort (claims database)
The MarketScan Commercial Claims and Encounters database Antithyroid (MMI only) drug use within 6 months before the pregnancy start date or during pregnancy. unexposed, sick
No Antithyroid (MMI or PTU) drug use in women with thyrotoxicosis before/during pregnancy.
3 months (or more) before pregnancy or during pregnancy 108 / 3236 NA
Prescription drug claims were used to determine ATD therapy.
Lo (control exposed to PTU)
2015
USA
1996 - 2010
retrospective cohort (claims database)
Kaiser Permanente Northern California (KPNC) Pregnant women with a maternal diagnosis of thyrotoxicosis and treated with MMI only during pregnancy. exposed to other treatment, sick
Pregnant women with a maternal diagnosis of thyrotoxicosis and treated with PTU only during pregnancy.
during pregnancy (anytime or not specified) 30 / 507 NA
Kaiser Permanente Northern California (KPNC) is a large integrated health care delivery system. Pharmacologic exposures were obtained from health plan electronic databases.
Lo (control unexposed, sick)
2015
USA
1996 - 2010
retrospective cohort (claims database)
Kaiser Permanente Northern California (KPNC) Pregnant women with a maternal diagnosis of thyrotoxicosis and treated with MMI only during pregnancy. unexposed, sick
Pregnant women with a maternal diagnosis of thyrotoxicosis and with no ATD and no thyroid hormone during pregnancy.
during pregnancy (anytime or not specified) 30 / 1171 NA
Kaiser Permanente Northern California (KPNC) is a large integrated health care delivery system. Pharmacologic exposures were obtained from health plan electronic databases.
McCarroll (Buckinghamshire control group)
1976
Ireland
1960 - 1971
retrospective cohort
Database of the Metabolic Unit, Royal Belfast Hospital for Sick Children, Belfast Children born to carbimazole-treated thyrotoxic women. unexposed, disease free
Original Buckinghamshire group
throughout pregnancy 25 / 6160 NA
Carbimazole was administered in every case during the first two trimesters of pregnancy then reduced in the last trimester.
McCarroll (Northern Ireland control group)
1976
Ireland
1960 - 1971
retrospective cohort
Database of the Metabolic Unit, Royal Belfast Hospital for Sick Children, Belfast Children born to carbimazole-treated thyrotoxic women. unexposed, disease free
Northern Ireland boys and girls obtained from medical inspections made in 1972.
throughout pregnancy 25 / 20 NA
Carbimazole was administered in every case during the first two trimesters of pregnancy then reduced in the last trimester.
Momotani
1984
Japan
1965 - 1980
retrospective cohort
Database of the Ito Thyroid Clinic and Hospital Infants whose mothers were treated with MMI during 1st trimester and were hyperthyroid or euthyroid. unexposed, sick
Infants whose mothers were not treated with MMI during 1st trimester and were hyperthyroid or euthyroid.
1st trimester 243 / 400 Treated group: addition of « Treated, hyperthyroid » and « Treated, euthyroid ». Unexposed: addition of « Untreated, hyperthyroid » and « Untreated, euthyroid ». NA
Treatment administered by physicians in the clinics.
Momotani (control exposed to PTU)
1997
Japan
Not specified
prospective cohort
Ito Hospital, Tokyo, Japan Pregnant women with Graves’ disease who continued methimazole (MMI) until delivery. exposed to other treatment, sick
Pregnant women with Graves’ disease who continued propylthiouracil (PTU) until delivery.
throughout pregnancy 43 / 34 34 were treated with PTU (group P), and 43 were treated with MMI (group M) NA
Administration of MMI or PTU by investigators.
Seo (control exposed to PTU)
2018
Korea
2008 - 2014
retrospective cohort (claims database)
Korean National Health Insurance database At least one maternal prescription of MMI alone during the first trimester. exposed to other treatment, sick
At least one maternal prescription of PTU alone during the first trimester.
1st trimester 1120 / 9930 3 types of ATD exposure: PTU alone (n = 9930), MMI alone (n = 1120), and both PTU and MMI (n = 1841). 210 cases of carbimazole use were included in the MMI groups NA
National Health Insurance (NHI) database
Seo (control unexposed, NOS)
2018
Korea
2008 - 2014
retrospective cohort (claims database)
Korean National Health Insurance database At least one maternal prescription of MMI during the first trimester. unexposed (not otherwise specified)
Women who had no prescription claims for Antithyroid drugs (ATDs) from the beginning of pregnancy to the day before childbirth.
1st trimester 1120 / 2872109 3 types of ATD exposure: PTU alone (n = 9930), MMI alone (n = 1120), and both PTU and MMI (n = 1841). 210 cases of carbimazole use were included in the MMI groups NA
National Health Insurance (NHI) database
Wing (control exposed to PTU)
1994
USA
1974 - 1990
cohort
High-risk obstetrics clinic database Pregnant women who were diagnosed with or had a history of hyperthyroidism treated with methimazole only during pregnancy. exposed to other treatment, sick
Pregnant women who were diagnosed with or had a history of hyperthyroidism treated with propylthiouracil only during pregnancy.
1st trimester, during pregnancy (anytime or not specified) 36 / 99 A cohort was established to compare the outcome of patients treated with propylthiouracil and methimazole. NA
The patients were followed up prospectively during pregnancy with treatment administration.
Wing (control unexposed, sick)
1994
USA
1974 - 1990
cohort
High-risk obstetrics clinic database Pregnant women who were diagnosed with or had a history of hyperthyroidism treated with methimazole only during pregnancy. unexposed, sick
Patients who were either euthyroid throughout pregnancy and required no medications or were hyperthyroid but were seen late in pregnancy.
1st trimester, during pregnancy (anytime or not specified) 36 / 43 A cohort was established to compare the outcome of patients treated with propylthiouracil and methimazole. NA
The patients were followed up prospectively during pregnancy with treatment administration.
Yoshihara (control exposed to PTU)
2012
Japan
1999 - 2010
retrospective cohort
Database of Ito Hospital, Tokyo, Japan Mothers who received MMI for the treatment of Graves’ disease in the first trimester of pregnancy (0 –12 wk gestation). exposed to other treatment, sick
Mothers who received PTU for the treatment of Graves’ disease in the first trimester of pregnancy (0 –12 wk gestation).
1st trimester 1426 / 1578 Compare the proportions of infants born with congenital malformations to mothers in the groups treated with each of the antithyroid drugs and to the mothers who were not treated with any antithyroid drugs during the first trimester of pregnancy. NA
Review of the medical records.
Yoshihara (control unexposed, sick)
2012
Japan
1999 - 2010
retrospective cohort
Database of Ito Hospital, Tokyo, Japan Mothers who received MMI for the treatment of Graves’ disease in the first trimester of pregnancy (0 –12 wk gestation). unexposed, sick
Mothers who received no medication for the treatment of Graves’ disease during the first trimester of pregnancy (0 –12 wk gestation).
1st trimester 1426 / 2065 Compare the proportions of infants born with congenital malformations to mothers in the groups treated with each of the antithyroid drugs and to the mothers who were not treated with any antithyroid drugs during the first trimester of pregnancy. NA
Review of the medical records.
Yoshihara (Controls exposed to PTU)
2021
Japan
2015 - 2019
retrospective cohort
Database of Ito Hospital, Shibuya-ku, Tokyo, 150-8308, Japan Mothers with Graves disease (GD) treated with thiamazole (MMI) alone during the first trimester of pregnancy (0-12 weeks’ gestation). exposed to other treatment, sick
Mothers with Graves disease (GD) treated with propylthiouracil (PTU alone during the first trimester of pregnancy (0-12 weeks’ gestation).
1st trimester 23 / 541 NA
Not specified (Pregnant patients being treated at the institution were informed during their pregnancy that they would be asked about the outcome of their pregnancy after delivery).
Yoshihara (Controls unexposed, sick)
2021
Japan
2015 - 2019
retrospective cohort
Database of Ito Hospital, Shibuya-ku, Tokyo, 150-8308, Japan Mothers with Graves disease (GD) treated with thiamazole (MMI) alone during the first trimester of pregnancy (0-12 weeks’ gestation). unexposed, sick
Women with Graves disease (GD) that had not been treated with any medication for GD in the first trimester of pregnancy (427 were in remission after ATD therapy for GD before their pregnancy, and all the others had been treated for GD before their pregnancy).
1st trimester 23 / 475 NA
Not specified (Pregnant patients being treated at the institution were informed during their pregnancy that they would be asked about the outcome of their pregnancy after delivery).

Case-control studies

Study Country
Study period
Study design
Data source Case Control Exposition Exposition period Sample size
(exposed/unexposed) Or (case / control)
Remarks Overall risk of bias
Banhidy
2011
Hungary
1980 – 1996
case control
Hungarian Case–Control Surveillance of Congenital Abnormalities (HCCSCA) Fetus/infants affected with major Congenital anomaly, selected from the data set of the Hungarian Congenital Abnormality Registry (HCAR), born of mother with hyperthyroidism. Newborn infants without any Congenital anomaly, selected from the National Birth Registry of the Central Statistical Office for the HCCSCA, born of mother with hyperthyroidism. Mothers were asked to send us the prenatal maternity logbook (obstetricians recorded maternal diseases, and related drug prescriptions in this logbook, in the first prenatal care visit was between the 6th and 12th gestational week) and other medical records particularly discharge summaries. at least 1st trimester, during pregnancy (anytime or not specified) 71 / 116 Of 71 case mothers, four (5.6%), while of 116 control mothers, eight (6.9%) were treated with antithyroid drugs. NA
Diagnosis of Congenital Anomalies was based on the compulsory notification of physicians to the HCAR. Pathologists sent a copy of the autopsy report to the HCAR if defects were identified in stillbirths and infant deaths.
Barbero
2008
Argentina
1976 - 2006
case control
Three hospitals in Buenos Aires city, Argentina Patients with unilateral or bilateral choanal atresia who received surgical treatment during the period 1976–2006. Children without choanal atresia but treated at the same centers because of other respiratory diseases A structured questionnaire was applied to all the mothers of eligible patients containing exposure during pregnancy, notably to acute and chronic maternal diseases, and medicines (detailed on the period/dose of MMI intake was also obtained (MMI is the only antithyroid drug available in Argentina)). 1st trimester 61 / 183 Non exposed women had mainly not reported hyperthyroidism (only in 2 (2/183) controls’ mothers). NA
Cases of choanal atresia were selected among patients of 3 hospitals in Argentina.
Clementi
2010
International (twelve surveillance programs)
Not specified
case control
International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR) Cases with the specific malformation being tested and reported first-trimester exposure to medication. Cases with any other malformation and reported first-trimester exposure to medication. Not specified. The coverage, structure, methods, and sources of ascertainment, de- scribed elsewhere, varied from program to program (12 surveillance programs included). 1st trimester -9 / -9 “exposed case-only” design: all infants had a major birth defect and were exposed to some medication. TOTAL: 18131 cases with malformations and reported first-trimester exposure to medication. NA
These data were reviewed for malformation classification by a clinician with expertise in genetics and dysmorphology to separate subjects of isolated major malformations from those of multiple congenital anomalies.
Khoury
1989
USA
1981 - 1983
case control
Atlanta Birth Defects Case-Control Study (ABDCCS) including cases of the Metropolitan Atlanta Congenital Defects Programme Stillborn and liveborn babies with birth defects (cases were classified into 66 broad and specific birth defect groups) A random sample of babies without birth defects, frequency-matched to cases by race, hospital of birth, and period of birth. Mothers of cases and controls were interviewed using a computer-assisted telephone questionnaire, notably whether or not they took medications for their illness, the names of specific medications, duration of treatment and intake of such medications during the index pregnancy. during pregnancy (anytime or not specified) 4904 / 3027 NA
Cases came from the Metropolitan Atlanta Congenital Defects Programme (MACDP). Babies with malformations are ascertained via multiple methods by Centres for Disease Control trained staff, including review of hospital records, vital records, cytogenetic laboratories and specialised clinics.

See the method used to produce these results