The exact underlying cause of limb-body wall complex (LBWC) is currently unknown. However, scientist have proposed the following three theories as possible explanations for the condition:
(1) Amniotic bands - LBWC occurs when the amniotic sac (the fluid-filled sac that surrounds the baby) breaks early, leading to the development of amniotic bands. These bands can cause amputations and constrictions in the developing baby. The timing of this event may explain the varying severity from case to case.
(2) Vascular "disruption" - LBWC is caused by a disruption of blood flow in the developing baby. This is a common explanation for certain types of birth defects, especially limb abnormalities.
(3) Abnormal embryonic folding - Early in development, the embryo folds to ensure the proper development and placement of different body parts and organs. If this event doesn't take place or if the embryo folds abnormally, it could lead to the various signs and symptoms associated with LBWC.
The majority of cases are considered to be sporadic, regardless of underlying cause and recurrence risk is considered to be low; however, there is at least one case reported in the medical literature of a woman having two different pregnancies with LBWC.
Recently, some authors have proposed a potential genetic origin of LBWC involving mutations in genes related to laterality (left or right side of the body) and caudal development (the lower half of the body). More genetic studies on infants with LBWC are needed to prove this connection.
Last updated: 3/10/2016
How could limb-body wall complex be present in one twin-but not in the other?
While all pregnancies have a background risk for congenital anomalies, twin pregnancies have an increased risk. It is estimated that congenital anomalies occur in about 10% of monozygotic twins. When one twin has an anomaly that is not present in the other, it is known as discordance. There are many theories regarding how discordance might occur in twins. Some propose that the twinning process itself might be involved, while others suspect there might be disruptions in shared placental circulation. One theory suggests that early amniotic rupture leads to the formation of amniotic bands. No single theory seems to be widely accepted or to explain the range of anomalies seen in monozygotic twin pregnancies.
We were not able to locate an estimate of how often twin pregnancies are discordant for limb-body wall complex; however, we did locate an article that described two cases in the literature with discordance. One case was a dizygotic twin pregnancy. The zygosity of the other case was not reported.
Last updated: 3/10/2016
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
Chih-Ping Chen, Maw-Shuan Lee, Fuu-Jen Tsai, Ming-Chao Huang, Schu-Rern Chern, Wayseen Wang. Limb-Body Wall Complex In One Fetus Of A Dizygotic Twin Pregnancy Conceived By Egg Donation, In Vitro Fertilization And Embryo Transfer:Prenatal Diagnosis And Literature Review. Taiwan J Obstet Gynecol. December 2009; 48(4):446-450. http://www.ncbi.nlm.nih.gov/pubmed/20045776.