Advise on Baby

Christine • Mommy & Wife ❤️

My doctor called me about my ultrasound. My due date was may 21 now it’s may 19 she said the baby was measuring 8 weeks 5 days last Thursday . How can the measurement change ? Is it just the baby is tall ? I’m so confused . The last ultrasound before this one the measurement was 6 weeks . Just confused on how it changes .