Is Flight Journey Recommended During Pregnancy?

I am 36 years old, am 1.68m tall and weigh 80kg. I have had 2 previous miscarriages, 1 at 8 weeks and 1 at 7 weeks. I am now 16 weeks pregnant and everything has been fine up until last week when I started bleeding. It was brown blood and I went to the hospital and gynae who checked and told me that the cervix is closed, the baby is fine and growing well and that everything else looks fine. The bleeding lasted 4 days. I am due to take an 18 hour flight in a weeks time, stay on holiday for a week and then return. Is it safe for me to fly or will I be putting the baby and this pregnancy at risk?