A Houston doctor working at Texas Children’s Hospital says uncertainty over travel restrictions from Iran are stopping him from performing life-saving surgery on unborn babies.

Dr. Alireza Shamshirsaz is a green card holder. That means he is a legal permanent resident of the U.S., currently able to travel freely between the countries. However, the fetal surgeon fears that travel restrictions could change while he’s overseas, keeping him from returning to the U.S.

“The fear of if I go outside, I cannot come back,” Dr. Shamshirsaz said. “My wife is here, my work is here, my entire work is here in the United States.”

Since 2014, the Iranian-born doctor has traveled back to Iran ever couple months to perform planned surgeries on high-risk pregnancies. After canceling his flights, the doctor told two Iranian mothers, one pregnant with twins, he would not be making the trip.

“Both parents will lose their pregnancy,” Dr. Shamshirsaz said. “The hardest park was when I called these patients, because I need to talk to them through Skype, and that was the hardest part.”

Doctor Shamshirsaz’s team performs one to two similar life-saving surgeries per day in the U.S. However, when he returns to Iran, he’s the only doctor in the country able to do surgery on babies before birth.

“Hopefully we can separate science and medicine from politics. We can separate the need of the people for medicine and help the people,” Dr. Shamshirsaz said. “It’s based on charity -- not based of making money or working for the government.”

After a federal appeals court decided Thursday to keep in place an order temporarily blocking the federal government from enforcing President Trump’s travel restriction. The president tweeted Thursday night, "SEE YOU IN COURT, THE SECURITY OF OUR NATION IS AT STAKE!”

Friday, President Trump said he’s considering signing a "brand new order" on immigration.