"Be fruitful!" the Grand Duke of Tuscany had enjoined his niece, and Marie de Médicis proved that she was up to the task. The Dauphin Louis (the future Louis XIII) was born at Fontainebleau on 27 September 1601, in the presence of princes of the blood as if to mark the importance of the event. Over the next nine years, the queen gave France no less than five more children. In addition to Louis, there was Elisabeth (22 November 1602), Chrétienne (or Christine, 10 February 1606), Nicolas, duc d’Orléans (16 April 1607), Gaston-Jean-Baptiste, duc d’Anjou (25 April 1608) and Henriette (26 November 1609), the future wife of Charles I, the king of England.
With six legitimate children by the queen of France, Henri IV appeared to have solidly set the Bourbon dynasty on the throne of France. In addition, his multiple liaisons made him one of the most prolific monarchs in the history of France. Jean-Claude Cuignet has counted six illegitimate children, and seven others who were made legitimate. They include César (7 June 1594), Catherine-Henriette (11 November 1596) and Alexandre de Bourbon (15 April 1598) with Gabrielle d’Estrées; Gabrielle-Angélique (21 January 1603) and Gaston-Henri de Bourbon (3 November 1601) with Henriette d’Entragues; Antoine de Bourbon (9 May 1607) with Jacqueline de Bueil and Jeanne-Baptiste de Bourbon (22 February 1608) with Charlotte des Essarts.
A quick glance at these dates shows that Henri kept busy with wife and mistresses simultaneously. The most flagrant example of this was his relationship with Henriette d’Entragues, at a time when he had just married Marie de Médicis. The two women gave birth almost at the same time (Louis and Gaston-Henri de Verneuil were born on 27 September and 27 October 1601; and Princess Elisabeth and Gabrielle-Angélique, were delivered on 22 November 1602 and 21 January 1603), which was accompanied by quarrels between Henri and Marie, who refused to put up with his "double life".
Henri tolerated these outbursts, because he was satisfied as a man, a husband, a king and a father. To Marie's great despair, he insisted that all his children be raised together, legitimate and illegitimate alike. The château de Saint-Germain-en-Laye became a veritable nursery, under the firm hand of governess Madame de Montglat. He would often pay surprise visits to his offspring, especially the Dauphin, with whom he played and swam in the Seine. He also knew how to punish, recommending in 1607 that Madame de Montglat "flog [the Dauphin] whenever he is stubborn or does something wrong, as I know well that there is nothing in the world that would do him so much good as that […]". Posterity has preferred to retain the image the ageing king playing with all of his children.