Heart Defect

I started taking Singulair the first part of 2010 after being sick for 4 months and 4 rounds of antibiotics. After 2 days of taking Singulair my sinuses cleared right up. I did try to stop taking it a few times and my allergies would flare back up within a few days of not taking it. About 3 months into the year I found out I was pregnant. They said I could take the medication throughout the pregnancy. My daughter was born with a heart defect that thankfully was fixed but had to have open heart surgery at 4 days old. She is my 4th child and I've never had any complications before and I just wonder if maybe it is related to the medication at all. It is the only thing I've done different from any of my other pregnancies. I don't know for sure I was just curious if anyone else has experienced any issues like this?