It is quite general issue of hair loss during pregnancy ..
The hair fall in the both cases happens due to the change that can be found in the chemical balance of their body. At this period of time, normally the hair production mechanism tends to break down.

To avoid this:
you can consult with your physician first in order to ensure the proper balance of hormones in your blood.
Try to have these nutrients in your daily diet:
Vitamin C with bioflavonoids
Vitamin B complex
Vitamin E
Zinc..
Try to use silica and biotin enriched shampoos and conditioners.
I think this tips will help to reduce and stop hair falling during the pregnancy..

hair fall may also occur due to lack of calcium as well..

shedding of hair or hair loss occurs during pregnancy due to vitamins and minerals deficiency. that is why it is important to to take supplements during pregnancy not just for the baby but for you as well.