Table 2.

The methods of acupuncture and chosen acupoints of the enrolled studies.

References	Acupuncture and acupoints
Lee et al., 2008 [15]	Needle acupuncture, 4 points; CV1 (GuanYuan), CV4 (Huiyin), SP6 (Saninjiao), SP9 (Yinlinquan)
Lee and Lee, 2009 [16]	Electroacupuncture, 6 points; bilaterally; BL32 (zhongliao), BL33 (ciliao), GB30 (huantiao)
Qi and Wu, 2012 [17]	Needle acupuncture, 7 points; CV1 (Huiyin), CV3 (Zhongji), CV4 (GuanYuan), SP9 (Yinlingquan, bilateral), SP10 (Xuehai, bilateral)
Liu et al., 2012 [18]	Needle acupuncture, 6 points; CV4 (GuanYuan), ST28 (Shuidao), SP6 (Sanyinjiao), LIV3 (Tai Chong), EXHN1 (Sishencong), BL54 (Zhibian)
Ma et al., 2014 [19]	Catgut embedding therapy; SP6 (Sanyınjiao), CV2 (Qugu), CV1 (Huiyin), ST36 (Zusanli), CV3 (Zhongji), BL23 (Shenshu)
Zhao and Sun, 2014 [20]	Needle acupuncture, 3 points; LU7 (Lieque), SI3 (Houxi), SP4 (Gongshun)
Küçük et al., 2015 [21]	Electroacupuncture, 6 points; UB 28 (Pang Guang Shu), GB 41 (Zu Lin Qi), LIV 3 (Tai Chong), SP 6 (Sanyinjiao), SP 8 (Diji), LI 4 (He Gu)
Sahin et al., 2015 [22]	Needle acupuncture, 7 points; BL33 (Zhongliao), BL34 (Xialiao), BL54 (Zhibian), CV1 (Huiyin), CV4 (Guanyuan), SP6 (Sanyinjiao), SP9 (Yinlingquan)
Chen et al., 2016 [23]	Needle acupuncture;
	Head-points:GV24 (Shenting), GV22 (Xinhui), GV21 (Qianding), GV20 (Baihui), BL6 (Chengguang), BL7 (Tongtian), etc.
	Body-points:CV3 (Zhongji), BL28 (Pangguangshu), BL32 (Ciliao), etc.
Gen et al. 2016, [24]	Needle acupuncture;
	Head-points:EXHN1 (Sishencong), GV20 (Baihui);
	Abdomen-points:CV3 (Zhongji), CV4 (Guanyuan), CV6 (Qihai);
	Leg-points:SP9 (Yinlingquan), GB34 (Yanglingquan), SP6 (Sanyınjiao), ST36 (Zusanli).
Qin et al. 2018, [25]	Needle acupuncture, 4 points; BL33 (Zhongliao), BL23 (Shenshu), BL35 (Huiyang), SP6 (Sanyinjiao)