In 1536, Henry's older brother, Francis, caught a chill after a game of tennis, contracted a fever and died shortly after, leaving Henry the heir.
Suspicions of poison abounded, from Catherine to Emperor Charles V. Sebastiano de Montecuccoli confessed under torture to poisoning the Dauphin.

As dauphine, Catherine was expected to provide a future heir to the throne.
According to the court chronicler Brantôme, "many people advised the king and the Dauphin to repudiate her, since it was necessary to continue the line of France".
Divorce was discussed.
In desperation, Catherine tried every known trick for getting pregnant, such as placing cow dung and ground stags' antlers on her "source of life", and drinking mule's urine.
On 19 January 1544, she at last gave birth to a son, named after King Francis.

After becoming pregnant once, Catherine had no trouble doing so again.
She may have owed her change of fortune to the physician Jean Fernel, who had noticed slight abnormalities in the couple's sexual organs and advised them how to solve the problem.
Catherine quickly conceived again and on 2 April 1545 she bore a daughter, Elisabeth.
She went on to bear Henry a further eight children, six of whom survived infancy, including the future Charles IX (born 27 June 1550); the future Henry III (born 19 September 1551); and Francis, Duke of Anjou (born 18 March 1555).
The long-term future of the Valois dynasty, which had ruled France since the 14th century, seemed assured.

Catherine's ability to bear children, however, failed to improve her marriage.
About 1538, at the age of 19, Henry had taken as his mistress the 38-year-old Diane de Poitiers, whom he adored for the rest of his life.
Even so, he respected Catherine's status as his consort.
When King Francis I died on 31 March 1547, Catherine became queen consort of France.
She was crowned in the basilica of Saint-Denis on 10 June 1549.
In 1536, Henry's older brother, Francis, caught a chill after a game of tennis, contracted a fever and died shortly after, leaving Henry the heir. Suspicions of poison abounded, from Catherine to Emperor Charles V. Sebastiano de Montecuccoli confessed under torture to poisoning the Dauphin.
As dauphine, Catherine was expected to provide a future heir to the throne. According to the court chronicler Brantôme, "many people advised the king and the Dauphin to repudiate her, since it was necessary to continue the line of France". Divorce was discussed. In desperation, Catherine tried every known trick for getting pregnant, such as placing cow dung and ground stags' antlers on her "source of life", and drinking mule's urine. On 19 January 1544, she at last gave birth to a son, named after King Francis.
After becoming pregnant once, Catherine had no trouble doing so again. She may have owed her change of fortune to the physician Jean Fernel, who had noticed slight abnormalities in the couple's sexual organs and advised them how to solve the problem. Catherine quickly conceived again and on 2 April 1545 she bore a daughter, Elisabeth. She went on to bear Henry a further eight children, six of whom survived infancy, including the future Charles IX (born 27 June 1550); the future Henry III (born 19 September 1551); and Francis, Duke of Anjou (born 18 March 1555). The long-term future of the Valois dynasty, which had ruled France since the 14th century, seemed assured.
Catherine's ability to bear children, however, failed to improve her marriage. About 1538, at the age of 19, Henry had taken as his mistress the 38-year-old Diane de Poitiers, whom he adored for the rest of his life. Even so, he respected Catherine's status as his consort. When King Francis I died on 31 March 1547, Catherine became queen consort of France. She was crowned in the basilica of Saint-Denis on 10 June 1549.
Catherine de' Medici