There are some very mystical reasons as to why pregnant women refrain from entering a cemetery. If you have this custom, and you wish to visit SFJC, you may stay within the area where a Kohain is allowed to be (the driveway and the grass between the driveway and the hedges along the driveway).
On a much more practical level, pregnant women will sometimes refrain from entering a cemetery because confrontation with death, and the emotionally charged situation of a funeral may cause her distress which may have a negative impact on her or her baby. It’s a personal choice for each individual to make.