褚澄曰∶合男女必当其年，男虽十六而精通，必三十而娶。女虽十四而天癸至，必二十而嫁。皆欲阴阳完
实，然后交而孕，孕而育，育而为子坚壮强寿。今未笄之女，天癸始至，已近男色，阴气早泄，未完而伤，未
实而动，是以交而不孕，孕而不育，育而子脆不寿。
《圣济经》曰∶天地者，形之大也。阴阳
者，气之大也。唯形与气，相资而立，未始偏废。男女媾精，万物化生，天地阴阳之形气寓焉。语七八之数，
七，少阳也；八，少阴也，相感而流通。故女子二七天癸至，男子二八而精通，则以阴阳交合而兆始故也。
胡孝曰∶男女交媾，其凝结成胎者，虽不离精血，犹为后天滓质之物，而一点先天之气萌于情欲之感者，
妙合于其间。朱子所谓禀于有子之初，《悟真篇》所谓生身受气初者是也。医之上工，因人无子，语男则主于
精，语女则主于血。着论立方，男子以补肾为要，女子以调经为先。又参以补气行气之说，察其脉络，究其
盈亏，审而治之，然后一举可孕也。
陈楚良曰∶人身气血，各有虚实寒热之异，唯察脉可知。舍脉而独言药者，妄也。脉不宜太过而数，数则
为热。不宜不及而迟，迟则为寒。不宜太有力而实，实者正气虚，而火邪乘之以实也。治法当散郁以伐其邪，邪
去而后正可补。不宜太无力而虚，虚乃气血虚也。治法当补其气血。又有女子气多血少，寒热不调，月水违期，
皆当诊脉，而以活法治之。务使夫妇之脉和平有力，交合有期，不妄用药，乃能生子也。
慎斋按∶以上四条，序嗣育之道，必阴阳完实，形气相资，兆始于先天有生之初，而再诊以脉之和平，始可
有子也。
褚澄说：男女交合必须年龄相当。男子虽然十六岁精气已通，但一定要等到三十岁才娶妻。女子虽然十四岁天癸（月经）已至，但一定要等到二十岁才出嫁。都要等到欲望和阴阳之气完备充实之后，然后进行交合才能受孕，受孕后能顺利生育，生下的孩子才会坚固强壮、长寿。如今那些尚未行笄礼（成年）的女子，天癸刚刚到来，就接近男子，导致阴气过早泄漏，身体尚未发育成熟就已受伤，元气尚未充实就已妄动，因此交合而不能受孕，即使受孕也不能顺利生产，生下的孩子脆弱且不长寿。
《圣济经》说：天地是形体中最大的存在。阴阳是气中最大的存在。只有形与气相互依赖才能成立，从未有过偏废的情况。男女交合精气，万物由此化生，天地阴阳的形与气蕴含其中。谈论七八之数，七属于少阳；八属于少阴，二者相互感应而流通。所以女子十四岁（二七）天癸至，男子十六岁（二八）精气通，这是因为阴阳交合而孕育生命起始的缘故。
胡孝说：男女交媾，其凝结成胎的部分，虽然离不开精血，但仍属于后天形成的渣滓物质，而一点先天的元气萌动于情欲之感之中，奇妙地融合在其中。这就是朱熹所说的“禀于有子之初”，以及《悟真篇》所说的“生身受气初”。高明的医生，针对没有子女的情况，论述男性时以精为主，论述女性时以血为主。撰写论文和制定方剂时，治疗男子以补肾为关键，治疗女子以调经为先务。再参考补气、行气的理论，观察其脉络，探究其盈亏状况，审慎地进行治疗，然后才能一举成功受孕。
陈楚良说：人身的气血，各有虚实寒热的不同，只有通过诊察脉象才能知晓。舍弃脉象而单独谈论用药，是荒谬的。脉象不宜过于急促且频率快（数脉），频率快则代表热证。不宜迟缓（迟脉），迟缓则代表寒证。不宜过于有力且坚实（实脉），所谓实，往往是正气虚弱，而火邪乘虚而入表现为实证。治疗方法应当疏散郁结以祛除邪气，邪气去除后才能补益正气。不宜过于无力且虚弱（虚脉），虚弱乃是气血两虚。治疗方法应当补益气血。又有女子气多血少，寒热不调，月经周期紊乱，都应当诊察脉象，并用灵活的方法治疗。务必使夫妇双方的脉象平和有力，交合有定时，不胡乱用药，这样才能生育子女。
慎斋按语：以上四条，阐述了生育后代的道理，必须阴阳完备充实，形与气相互资助，生命起始于先天有生之初，再通过诊察脉象是否平和，才可以拥有子女。
Chu Cheng stated: Sexual intercourse between men and women must occur at appropriate ages. Although a man's essence may become clear at sixteen, he should not marry until thirty. Although a woman's Tian Gui (menstruation) may arrive at fourteen, she should not marry until twenty. Both parties must wait until their desires and Yin-Yang Qi are complete and substantial before engaging in intercourse to conceive. Only then can conception lead to gestation, gestation to childbirth, and the child will be robust, strong, and long-lived. Nowadays, girls who have not yet undergone the Ji Li ceremony (coming-of-age ritual) have just begun menstruation; if they approach men prematurely, their Yin Qi leaks too early. Their bodies are injured before fully developed, and their movements are initiated before their vitality is solidified. Consequently, intercourse fails to result in conception; if conception occurs, it fails to sustain pregnancy; if the child is born, it is fragile and short-lived.
The *Shengji Jing* states: Heaven and Earth are the largest forms. Yin and Yang are the greatest Qi. Form and Qi rely on each other for existence and never neglect one another. When men and women join their essences, all things are transformed into life; the form and Qi of Heaven and Yin and Yang are embedded within this process. Regarding the numbers seven and eight: seven belongs to Shao Yang (Lesser Yang); eight belongs to Shao Yin (Lesser Yin). They interact and flow through mutual resonance. Therefore, when a girl reaches fourteen (two sevens), her Tian Gui arrives, and when a boy reaches sixteen (two eights), his essence becomes clear, it is because the beginning of life is signaled by the intersection of Yin and Yang.
Hu Xiao stated: In sexual intercourse, the part that condenses to form the fetus, although inseparable from essence and blood, still consists of post-natal dross-like substances. However, a spark of pre-natal Qi, awakened by emotional and desire-induced sensations, miraculously merges within. This corresponds to Zhu Xi's concept of "receiving endowment at the beginning of conception" and the *Wuzhen Pian*'s reference to "the initial reception of life and Qi." Expert physicians, addressing infertility, focus on essence for men and blood for women. In writing treatises and prescribing formulas, treatment for men prioritizes tonifying the Kidney, while treatment for women prioritizes regulating menstruation. Additionally, referencing theories of tonifying and moving Qi, observing meridians, investigating deficiencies or excesses, and treating with prudence allows for successful conception in one attempt.
Chen Chuliang stated: The Qi and Blood in the human body vary in deficiency, excess, cold, and heat, which can only be known through pulse diagnosis. Abandoning pulse diagnosis to speak solely of medication is absurd. The pulse should not be too rapid (Shu Mai); rapidity indicates Heat. It should not be too slow (Chi Mai); slowness indicates Cold. It should not be too forceful and firm (Shi Mai); what appears as Excess is often underlying Righteous Qi deficiency, with Fire Pathogens exploiting this to create an Excess pattern. The treatment method should be to disperse stagnation to eliminate pathogens; only after pathogens are removed can Righteous Qi be tonified. It should not be too weak and deficient (Xu Mai); deficiency indicates Qi and Blood insufficiency. The treatment method should be to tonify Qi and Blood. Furthermore, for women with abundant Qi and scant Blood, irregular cold and heat, and delayed menstruation, pulse diagnosis is essential, and flexible treatments should be applied. It is crucial that both husband and wife have peaceful and forceful pulses, engage in intercourse at appropriate times, and avoid reckless medication, thereby enabling them to bear children.
Shenzhai commented: The above four passages outline the principles of procreation. One must ensure Yin and Yang are complete and substantial, and Form and Qi support each other. Life begins with pre-natal endowment, and subsequent pulse diagnosis must confirm peace and harmony before one can successfully have children.