My one-year-old has just started teething and has four teeth coming in her cheeks are blotchy and read tonight is this a side effect of teething

Yes. Rosey cheeks are a sure sign that your toddler is teething and if I am not mistaken these are the first molars which tend to be especially bad. Good luck and liquid tylenol can be really useful to help your child through this.

As your child is one year old, I am assuming this isn't the first time she is teething. Most likely she has some teeth already. Correct?

Yes, red blotchy cheeks can be a symptom of teething, as can diarrhea, diaper rash and fever.