This study abstract says that there is actually very little academic literature examining the topic of pregnancy while sky-diving. Some salient points (formatted for easier reading):
RESULTS:Women do actively decide to skydive while pregnant.The majority of our participants were between 25-year-old and 35-year-old primips with 100 to 1000 jumps experience, answering the questionnaire from a European IP address.Precautions are taken in terms of weather conditions, gear, or sports partner.The literature review found no relevant literature regarding the question. Literature is searched for risk factors that come close to the ones in skydive (ie, oxygen saturation, shock forces, and others). Further studies are needed to show the long-term effect of stress or low O2 saturation on antenatal programming, or short-term hypoxia and pregnancy outcome in pregnant skydiving women and their offspring.
CONCLUSIONS:Pregnancy itself is a risk factor for injuries. Injuries in pregnancy are clearly associated with an unfavorable pregnancy outcome. The recommendation "do not skydive during pregnancy" is the safest approach. A possible lesser risk alternative to skydiving could be wind-tunnel training.
Clin J Sport Med. 2014 Mar 14. [Epub ahead of print]
Parachuting and Pregnancy: What Do We Know About Pregnant Skydivers and the Risks They Are Taking?
Ebner F1, Wöckel A, Janni W, Paterson H.