HELP!! is my baby ok???

Linda • 23, married, 3rd pregnancy, but first baby that stuck 😊🌈🎀
A nurse called me about my 20 week ultrasound, and she said "the cord insertion is too close to the placenta"
 What does this mean?????
She didn't explain it much, but said they want me to have another scan in 4 weeks to measure growth. Is my baby ok? My next midwife appointment isn't for another 4 weeks, and the nurse said the midwife will explain more at the appointment. That's not until April 15th!!