Pass function elements to render in js

I have in js a class function called contenidoNuevo() which triggers depending on the difference of dates I have in my web application. In the else statement I have a Card class which includes the line chart from react-chartjs-2. I would like to trigger the contenidoNuevo class in my render component. Now if my difference of days is different than 0, what displays is the Hola George!, if dates are different than 0, I want to display the graph. How can I achieve it? Thanks!

contenidoNuevo function:

contenidoNuevo = () => {
   if (this.state.difference_days != 0) {
     return <h1>Hola George!</h1>
   }
   else {
     console.log(this.state.prueba)

     <Card
         title="Conversaciones por día del mes"
         chartType="line"
         labels={Object.keys(this.state.day_month_conversation)}
         datasets={[
             {
                 label: 'Número de conversaciones actuales',
                 fill: false,
                 lineTension: 0.1,
                 backgroundColor: '#F07C30',
                 borderColor: '#FA6A01',
                 borderCapStyle: 'butt',
                 borderDash: [],
                 borderDashOffset: 0.0,
                 borderJoinStyle: 'miter',
                 pointBorderColor: '#F07C30',
                 pointBackgroundColor: '#FA6A01',
                 pointBorderWidth: 1,
                 pointHoverRadius: 5,
                 pointHoverBackgroundColor: '#F07C30',
                 pointHoverBorderColor: '#FA6A01',
                 pointHoverBorderWidth: 2,
                 pointRadius: 1,
                 pointHitRadius: 10,
                 data: Object.values(this.state.day_month_conversation)   
             }
         ]}
     />

    return Card
}

render():

render() {
  return (
   .
   .
   .

  <div className="row">
    <div className="col-12 mb-30">
      {this.contenidoNuevo()}
    </div>
  </div>
}