A high rate of pregnancy-related CTS was highlighted in an article in the Canadian Medical Association Journal in 1983, vol 128, indicating that 25% of 1000 consecutive postpartum women experienced CTS during pregnancy; 3/4 of them that experienced this had bilateral symptoms. Half of the multigravidas had had similar symptoms in previous pregnancies.
Most recently attention to this gestational complication in an article by Padua et al in Muscle & Nerve, Nov 2010, pp 697-702 in a thorough patient and literature review. They discussed some of the literature specifically trying to address the incidence of CTS and performed a metanalysis. A big problem in assuming rather than confirming CTS with NCS was identified in most of the over 200 papers they reviewed. They felt that the natural history of pregnancy-related CTS (PRCTS) varies considerably and often fails to resolve after child delivery and lactation, but that only 1/3 of the cases would resolve after 1 year and up to 2/3 after 3 years.
This study coincides with the literature reflecting that about 1/6 adults ultimately will develop CTS about 90% of whom will come in for treatment-if ever-after age 30. All studies agree that the likelihood of a woman developing CTS is twice that of a man. This correlates well with congenital narrowness of the carpal tunnel confirmed in previous research by Dekel et al as reported in their article Idiopathic Carpal Tunnel Syndrome Caused by Carpal Tunnel Stenosis, in the British Medical Journal, May 1980, and other reports reflecting sthe strong familial likelihood of developing CTS. This correlates well with other studies on carpal tunnel size as well as elevated carpal tunnel pressure in people with CTS and elimination of the elevated pressure after carpal tunnel release. Quite likely, if followed past age 30 I suspect over 80% of the subjects with NCS proved CTS will go on to require surgery i.e., the increased fluid of pregnancy serves as a challenge in congenitally narrowed carpal tunnels while the remainder of the physiologic triggers evolve by age 30 or so.