I read it somewhere that cardamom has blood loosening properties. During pregnancy the blood usually becomes watery. Cardamom will only add on to the water content in blood. So, better be safe and don’t consume it.
Cardamom has been listed as one of the spices to avoid during pregnancy in many websites. So, yes it is not a good spice if you are trying to conceive. Consuming cardamon during pregnancy increases the risk of miscarriage.