It is not recommended to send flowers, because flowers contain pollen, and many flower shops add some fragrances to flowers, which may be bad for the health of pregnant women and fetuses. However, you can send cartoon bouquets, which are made of small dolls. They are not harmful to pregnant women, and they never wither. They can be placed at home all the time. They are very practical and thoughtful.
It is recommended to send some warm fruits, or you can send your sister an anti-radiation suit, if she doesn't have one now, because pregnant women often go online, watch TV, etc., and having an anti-radiation suit is also a protection for the baby.
You can also buy a baby audiometer, which is a little like a doctor's stethoscope. It is a small instrument that can hear the baby's heartbeat. If your sister has such a treasure, she will definitely be very moved when she hears the heartbeat of her own baby in the belly.
In addition, you can also buy some books or CDs about prenatal education and early childhood education for your sister, or send some beautiful music CDs, so that the baby in the belly can enjoy beautiful music every day.