Not a medic, nothing is recommended but it sounds like Malarone is one of the least worst.
From www.netdoctor.co.uk:
If you are planning to travel to a malarious region or have any other travel vaccines, it is very important that you tell your doctor if you are pregnant or planning to become pregnant.
Medicines for pregnant women
Both chloroquine and proguanil have no special risk for pregnant women, and should be administered together. Pregnant women who use proguanil should also take a daily folic acid supplement.
In countries where resistance to chloroquine and proguanil is high, it may be necessary for your doctor to prescribe mefloquine. There is evidence that mefloquine may be associated with an increased risk of stillbirths, so it should only be used during pregnancy if the need for it is great.
The decision to prescribe mefloquine is made after weighing up the benefits of preventing malaria, versus the risks of harmful effects on the foetus and the risk of contracting the disease.
In scenarios where other medicines are not effective, the benefits of using mefloquine may outweigh the risks, but your doctor would need to decide this in conjunction with you. If pregnant women accidentally take mefloquine during pregnancy, there is no reason to terminate the pregnancy.
Malarone should be avoided unless there is no suitable alternative. Pregnant women who use Malarone should also take a daily folic acid supplement.
Doxycycline should not be taken by pregnant women.