Aerobics and Exercise During Early Pregnancy: A Doctor's Perspective

Question
Dear Dr. Rappaport,

My wife and I are currently "working" on a second child and have a quetsion with regards physical activity.  My wife is regularly going to aerobic and workout sessions.  She certainly is not doing excessive training and just started a few months ago with regular aerobic clases.  Now, how can aerobics and exercises such as abdominal trainng (e.g. push-ups etc...) affect child formation in an early stage of pregancy, typically befoere pregnancy is even known (e.g. first couple of weeks)?  In other words, is there a risk of malformation or poor development and should my wife stop exervising and training abdominal muscles?

Many thanks in advance for your time and advice,

Andreas Renken.

PS: you answered alraedy some question 3-4 years ago when we expected our first son, and I really liked your professional advice.  Taht's why I'm "coming back" to you now. I really admire professionals like you who are willing to give there advice without payment and do this regularly and for many years!  

Answer
There is no harm from continuing aerobic exercise or abdominal exercises while trying to conceive. Exercise or aerobics will not cause any developmental anomalies or malformations in the growing fetus. However, once your wife becomes pregnant, we advise to avoid aerobic exercises because oxygen is shunted towards the brain during aerobics, which takes oxygen away from the uterus, lowering perfusion to the baby.  In addition, once she is pregnant she can continue to exercise, but at around 18-20 weeks gestation, she will no longer have a waist and will not be able to perform the same abdominal exercises that she does now. She can still exercise quite vigorously during her entire pregnancy, but with some restrictions. If she becomes tired or exhausted, she must stop for awhile and rest.Good Luck to you both.