What could be worse than smoking cigarette everyday, for our health?
I would say
“Sofa” and “Bed rest”.
These two are the deadly combination that have been wrecking our health.
We all know that pregnant mother’s health directly influences the health of an unborn baby and its future as an adult. There is no time in human life, health is more important  during pregnancy than at any other time. It simply decides the fate of the generations to come.
Unfortunately in our culture ” Bed rest ” is considered one of the best health tips for pregnant mothers to practice. Grandmothers and mother in laws, are still a big influence on how much a pregnant woman moves around. Exercise is not dangerous for the unborn baby. Infact exercising women are less likely to face many health problems during their pregnancy, during the delivery time, after their delivery and ofcourse their rest of their lives
There are plenty of scientific evidence that suggests pregnant ladies should continue to be active for not only their sake but also, more importantly,  for the sake of the health of their babies.
The benefits of exercise during Pregancy are innumerable.. Here are some.
a) The more active and fit you are during pregnancy, the easier it will be for you to adapt to your changing shape and weight gain.
b) As your muscles that helps with delivering your baby becomes stronger, the labour becomes easier and shorter
c) Increased chances of normal delivery and helps avoid caeserian section
c) Chances of premature labour is reduced
d) Chances of Pregnancy induced hypertension is reduced
e) Better sugar levels in the mother
f) Lesser chances of becoming a diabetic after delivery
Keep up your normal routine physical activity and additionally do exercises to keep fit. Enjoy your favorite sports. Keep Walking, running, and dancing. Perhaps practice Yoga.
Recommendations :
Walking perhaps is the most feasible form of physical activity for the overwhelming majority of people. Scientific research that is published recently from Japan,  has quantified how far pregnant ladies should be  walking to overcome their diabetes, during pregnancy.
6000 steps per day to safe pregnancy. 6000 steps is approximately 4.5 kilometers. It may Sound too much for some of us. But if you have any plan to become pregnant, walking that far is likely to reap its benefits
The American College of Obstetricians and Gynecologists (ACOG) recommends at least 30 min of moderate‐intensity physical activity on most, if not all, days of the week

Recommendations for exercise during pregnancy are same as those for  healthy individuals. If you do regular exercises and  if you are very well accustomed to exercise then 30–40 minutes of moderate activity on most days of the week is good for you. If you are just beginning to exercise during the pregnancy, provided there are no contraindications , a light exercise intensity is recommended to begin with.

There are a few conditions and precautions :
Don’t take part in contact sports that could result in physical injuries such as boxing, judo or squash
If you have pregnancy related complication that warrants rest as suggested by your obstetrician.
Always consult with your Obstetrician regarding physical exercises
But Remember
We don’t stop playing because we grow old; we grow old because we stop playing.
Dr M Saravanan
Rio childrens and Maternity Hospital Madurai
Reference :
doi: 10.1111/jog.13698
Ayako Hayasi et all , Kyoto university