The epidemiology of conjoined twinning in Southern Africa

Abstract

Thirty‐one sets of conjoined twins were born in Southern Africa during the period February 1974 to May 1982 with a striking increase in incidence in 1974 and 1975. There was no ethnic or social predilection, but clustering of cases occurred in a remote area of Zimbabwe. No aetiological agent was discovered, and there was no seasonal variation in the time of conception. Female conjoined twins accounted for 62% of cases, and twenty sets were of the thoracopagus type. Four pairs were separated, three of which were of the xiphopagus subtype and have survived.

Multiple Pregnancies

“…This statement, however, has been criticized by Hanson ( 1975 ) . Dif fi culty of ascertainment is further discussed by Viljoen et al ( 1983 ) in a large series of conjoined twins from Southern Africa; contrary to earlier reports, these authors found no skewing in favor of the black population. Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly.…”

“…Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly. That suggestion was supported by Viljoen et al ( 1983 ) . The ultrasonographic diagnosis of conjoined twins can now be made as early as at 8 weeks' gestation (Lam et al 1997(Lam et al , 1998, and three-dimensional sonography is helpful in further diagnosis of their anomalies (Maymon et al 1998 ) .…”

Multiple Pregnancies

“…This statement, however, has been criticized by Hanson ( 1975 ) . Dif fi culty of ascertainment is further discussed by Viljoen et al ( 1983 ) in a large series of conjoined twins from Southern Africa; contrary to earlier reports, these authors found no skewing in favor of the black population. Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly.…”

“…Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly. That suggestion was supported by Viljoen et al ( 1983 ) . The ultrasonographic diagnosis of conjoined twins can now be made as early as at 8 weeks' gestation (Lam et al 1997(Lam et al , 1998, and three-dimensional sonography is helpful in further diagnosis of their anomalies (Maymon et al 1998 ) .…”

Conjoined twins: A worldwide collaborative epidemiological study of the International Clearinghouse for Birth Defects Surveillance and Research

“…This probably accounts for the differences observed within and between the four depicted categories when prevalence results were described (Table I). The underreporting is also a dilemma when present results are compared with previous reports [Hanson, 1975; Källén and Rybo, 1978; Edmonds and Layde, 1982; Viljoen et al, 1983; Castilla et al, 1988; ICBDMS, 1991; Liang et al, 1999; Tang et al, 2007] and other studies listed in Box II.…”

A Postnatal Incidental Diagnosis of Parapagus Disprospus Dibranchius Dipus with Discordant Craniorachischisis Totalis in a Resource-Limited Setting: a CASE REPORT

“…They are reported more frequently in the Black population and are more common among female fetuses (11). Overall, most conjoined twins are female, with a female-to-male ratio of approximately 3:1, although parapagus twins are more commonly male (2) There are two main theories regarding the embryonic pathogenesis of conjoined twins: the fusion and ssion theory. The fusion theory proposes for a secondary fusion between two initially distinct embryonic discs (12,13).…”

Multiple Pregnancies

“…This statement, however, has been criticized by Hanson ( 1975 ) . Dif fi culty of ascertainment is further discussed by Viljoen et al ( 1983 ) in a large series of conjoined twins from Southern Africa; contrary to earlier reports, these authors found no skewing in favor of the black population. Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly.…”

“…Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly. That suggestion was supported by Viljoen et al ( 1983 ) . The ultrasonographic diagnosis of conjoined twins can now be made as early as at 8 weeks' gestation (Lam et al 1997(Lam et al , 1998, and three-dimensional sonography is helpful in further diagnosis of their anomalies (Maymon et al 1998 ) .…”

Conjoined twins: A worldwide collaborative epidemiological study of the International Clearinghouse for Birth Defects Surveillance and Research

“…This probably accounts for the differences observed within and between the four depicted categories when prevalence results were described (Table I). The underreporting is also a dilemma when present results are compared with previous reports [Hanson, 1975; Källén and Rybo, 1978; Edmonds and Layde, 1982; Viljoen et al, 1983; Castilla et al, 1988; ICBDMS, 1991; Liang et al, 1999; Tang et al, 2007] and other studies listed in Box II.…”

A Postnatal Incidental Diagnosis of Parapagus Disprospus Dibranchius Dipus with Discordant Craniorachischisis Totalis in a Resource-Limited Setting: a CASE REPORT

“…They are reported more frequently in the Black population and are more common among female fetuses (11). Overall, most conjoined twins are female, with a female-to-male ratio of approximately 3:1, although parapagus twins are more commonly male (2) There are two main theories regarding the embryonic pathogenesis of conjoined twins: the fusion and ssion theory. The fusion theory proposes for a secondary fusion between two initially distinct embryonic discs (12,13).…”

Multiple Pregnancies

“…This statement, however, has been criticized by Hanson ( 1975 ) . Dif fi culty of ascertainment is further discussed by Viljoen et al ( 1983 ) in a large series of conjoined twins from Southern Africa; contrary to earlier reports, these authors found no skewing in favor of the black population. Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly.…”

“…Milham ( 1966 ) analyzed 22 sets and suggested local clustering of this anomaly. That suggestion was supported by Viljoen et al ( 1983 ) . The ultrasonographic diagnosis of conjoined twins can now be made as early as at 8 weeks' gestation (Lam et al 1997(Lam et al , 1998, and three-dimensional sonography is helpful in further diagnosis of their anomalies (Maymon et al 1998 ) .…”

Conjoined twins: A worldwide collaborative epidemiological study of the International Clearinghouse for Birth Defects Surveillance and Research

“…This probably accounts for the differences observed within and between the four depicted categories when prevalence results were described (Table I). The underreporting is also a dilemma when present results are compared with previous reports [Hanson, 1975; Källén and Rybo, 1978; Edmonds and Layde, 1982; Viljoen et al, 1983; Castilla et al, 1988; ICBDMS, 1991; Liang et al, 1999; Tang et al, 2007] and other studies listed in Box II.…”

A Postnatal Incidental Diagnosis of Parapagus Disprospus Dibranchius Dipus with Discordant Craniorachischisis Totalis in a Resource-Limited Setting: a CASE REPORT

“…They are reported more frequently in the Black population and are more common among female fetuses (11). Overall, most conjoined twins are female, with a female-to-male ratio of approximately 3:1, although parapagus twins are more commonly male (2) There are two main theories regarding the embryonic pathogenesis of conjoined twins: the fusion and ssion theory. The fusion theory proposes for a secondary fusion between two initially distinct embryonic discs (12,13).…”